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            FAQs FOR TI  AND CASIO GRAPHING CALCULATORS

CONTENT: Answers to a variety of problems with TI-82, TI-83 Plus, TI-89, and Casio graphing calculators.
There are several FAQs on scientific calculators.

How to search for  an answer on this sheet: In order to make maintenance of this sheet easier, I designed it so that you can use your browser to locate an answer.  After you've located the FAQ number that you want, just use the Find and enter the index number.  Be sure to enclose the number in parentheses or you'll not find the answer quickly.  The start point for the search should be below the listing in the index.

Index: (There are more FAQs on page 2.  Click "More Difficult Page 2"  under TI FAQs in the navigation panel to go there.)

(1) How do I graph both branches of the hyperbola √(4x^2+16) on a TI-83?
(2)  If I do i12 on a TI-83, I get 1+2E-13i. How do I get the right answer?
(3)  How do I raise a number to the one-half power on a TI-83.
(4)  How do I graph piecewise functions?
(5)  Please help.   I have no idea how to use the regression capabilities of my TI-83+ calculator. My problem is: I have the number of bankruptcies    (in thousands) for 18 years.
(6)  What's the best graphing calculator, and where's the best place to buy one?
(7)  How do I do the rref and ref on my TI-82 calculator as the other people in my class do on their TI-83?
(8)  How do I graph a circle on the TI-83?
(9)  How do I draw a circle on the TI-83?
(10)  How do I put text on a graph?
(11)  When I draw text on a graph and use the coordinates that I use for OUTPUT, the text overlaps.  Why?
(12)  How do I find the inverse of a matrix on the TI-83?
(13)  When I enter an equation with large coefficients, I often can't find the graph on my TI-83Plus.  How do I find it?
(14)  Is there a way to solve quadratics on a TI-83Plus?
(15)  Can I enter fractions and get answers in mixed numbers?
(16)  How do I find Sin, Cos, and other trig functions?   I keep getting answers that don't make sense.
(17)  Can I store pictures/graphs that I have made/drawn on my screen?
(18)  Is there a way to solve an equation on  the TI-83Plus without graphing?
(19)  How do I enter a matrix in a TI-83?
(20)  How do I solve a system of equations on the TI-83Plus?
(21)  How do I do matrix row operations with the TI-83Plus?
(22)  How do I find  the angle whose cos is 0.5?
(23)  How do I transfer a program from one TI-83 Plus to another TI-83 Plus?
(24)  Can I find the fractional equivalent for values such as Intersection and Zero?
(25)  Can I graph inequalities on the TI-83Plus?
(26) How do I set up the domain for a function on a TI-83?
(27)  How do I graph the residuals after I do a linear regression on the TI-83Plus?
(28)  How do I generate random numbers on a TI-83/TI-83Plus?
(29)  How do I store random numbers in a list and arrange them in order?
(30)  How do I calculate IRR on a possible investment?
(31)  How do I do a quartic regression and graph the scatter plot and the regression equation on the         same axis?
(32)  The TI-83+ selects the number of classes when I do a histogram.  Is there any way I can choose my own?
(33)  Do I really need to change the batteries on my TI-83+ when I upgrade the operating system?
(34)  Does the conics application for the TI-83+ provide the same graphing capability as the  graphing functions that are built into the calculator?
(35)  I've read various places on the Internet that there's not much difference between the TI-83+ and the TI-82.  Is that correct?
(36)  Is it possible to do a stem-and-leaf chart on the TI-83 Plus?
(37)  How do I find the critical numbers for y = x3 -x2 -3x +1 on my TI-83 Plus?
(38)  On my TI-82,  when I enter (-32)^(1/5); then (-2)^3 I get a correct answer, -8, but when I enter (-             32)^(3/5) I get Ma    ERROR.  Why?
(39)  My teacher says the TI-83Plus is useless for finding the derivative.  Why is that?
(40)  Can I draw points on the graph screen on my TI-83Plus?
 

DISCLAIMER:  The FAQs on this web site, and especially FAQ #6 here,  reflect the writer's subjective opinion and observations. The FAQs should be considered only as another source of information.  The writer is not endorsing any particular brand or model of the calculators mentioned or any particular store or shop. The writer does not warrant the accuracy of any FAQ.  Any calculator mentioned may not be a representative sample of what is on the market, and the manufacturers may change their products or specifications without my knowing about it.

Answers:
--------------------------------------------------------------------------------

(1)  How do I graph both branches of the hyperbola √(4x^2+16) on a TI-83?
Enter the following into Y1:
{1, -1} √(4x2 +16)

Or you can enter -Y1 into Y2 to get the second branch.
------------------------
(2) If I do i^12 on a TI-83, I get 1+2E-13i. How do I get the right answer?
Actually that is the correct answer from the calculator's perspective.  That's the answer written in rectangular form, a +bi.  The calculator considers 2E-13 to be zero, so the answer would be 1 + 0i in rectangular format. 
Here's a somewhat more detailed discussion of doing powers of "i" with the TI-83 Plus.
1. One simple way to raise "i" to a power,  as you probably know, is to divide the exponent by 4 and raise i to the remainder.
Ex: I^14 = 1^12 * i² = 1*(-1)= -1.
If you want to get a little trickier, you can use the fact that you can raise "i" up to powers where the units or tens digit is up to and including 6 without the 2E-13 or some such number..
Ex: i^66 = i^60 * i^6, and i^68 = i*60*i^6*i²
You can also do this:
i^12 = (i^3)^4, or i^14 = (i^6)^2*i² so long as the SUM of ALL the exponents is <12.
Actually though, all of this seems a little excessively tedious when all you need do is throw away the 2E-13 or whatever very small number you get. 
--------------------
(3) How do I raise a number to the one-half power on a TI-83.
Probably the easiest way, using 4 as an example, is this: 4^(1/2)
--------------------------
(4) How do I graph a piecewise function on a TI-83?
 
This is going to be a rather long answer. I assume you know that when you want to limit the domain of a function you use the inequalities obtained by pressing [2nd], [TEST] and selecting one of those. Yet there are a couple nuances that you need to know.
Students typically enter a problem as follows:  (x>3)2x +1. Now, the problem with that is that the test is only applied to 2x and the unwanted graph of y =1 appears on the screen. That's easily fixed by doing this:  (x>3)(2x+1).
      Still, some students complain that there's an extraneous vertical line where the graph goes from zero to the function. There are a couple of ways to fix that:
A) Press [MODE] and change from <Connected> to <Dot>. That's probably the best general method for eliminating extraneous lines on a TI-83 or TI-83 Plus..

So, let's take this problem, and see how we'd do it:
         {x+5 ; x< -2
f(x) {-2x-1 : -2 <x< 2
       { 2x-9 ; x > 2
One way to do this perfectly is as follows:
Y1= (x< -2)(x+5)
Y2= (-2<x)(x<2)(-2x-1)
Y2= (x>2)(2x-9)
The press [MODE],  change the display from [Connected] to [Dot].
Then press [GRAPH]

B) Here's the method I prefer:
I don't like switching back and forth between <Connected> and <Dot>. So, I prefer simply to divide the function by the test. Like this, for example:
Let's take the same problem and enter it like this:
Y1= (x+5)/(x< -2)
Y2= (-2x-1)/((-2<x)(x<2)
Y3= (2x-9)/(x>2)
(Actually, you won't need some of the parentheses enclosing the functions, but I sometimes use parentheses just so I won't have to figure out if I need them.)

      Using that method, in the region where the test is false, i.e., zero, the function is divided by zero and, so is undefined. So the calculator displays nothing. In the region where the test is true, the function is divided by 1. Notice in the Y2= , entry, that you must enclose each test in parentheses; then enclose the whole two tests in parentheses. Otherwise the calculator will divide by the first test, (-2<x), and multiply by the second, (x<2), and you'll get an extraneous return-to-zero line.
So, all you need to remember with this method is to divide by the tests, and be sure to use grouping symbols as the calculator needs them.
------------------------------------
(5) Please help I have no idea how to use the regression capabilities of my TI-83Plus calculator. My problem is: I have the number of bankruptcies (in thousands) for 18 years.
First you need to get your data in lists.
You can do it from the home  screen, but with that much data I prefer to enter it directly into the list tables. Here's how to do it:
[STAT], [ENTER]
Then enter the numbers 1 through 18 in L1 and the corresponding values in L2.
[2nd], [QUIT]
[STAT], Cursor to CALC, <7>, [ENTER] (Where <7> is just the number 7 from the keyboard.)
QuartReg will appear on the screen. Immediately after that enter the following:
[2nd], [L1] [,], [2nd], [L2], [, ] Note that the commas outside the brackets are just separators so you can tell what I'm doing. They do not appear in the syntax. Now, you want to store this as a Y-variable, say, Y1. So, do it this way:
[VARS], Cursor to Y-VARS, [ENTER], [ENTER]

You should now have this on your screen.  QuartReg L1, L2, Y1
Press [ENTER]
After a few seconds a long equation with coefficients having several decimal places will appear on the screen.
To graph that, you could just press GRAPH, but you probably won't get anything on the screen because of the WINDOW setting. So, do this:
[WINDOW]; Xmin = -3; Xmax = 20; Ymin = -3;Ymax = 2000; Yscl = 100; press [GRAPH]
That should do it.
-----------------------
(6)  What's the best graphing calculator, and where's the best place to buy one?
      

Caveat:  The following is an attempt to give some help to  those who are unfamiliar with the capabilities of  graphing calculators and how their capabilities relate to courses of study.  It is not intended as  definitive advice on what a particular student should buy.  I would appreciate knowing of any disagreements you have with me.  Send me an e-mail at the address listed elsewhere.

 Bottom LineTalk with the teachers of the classes you're going to be taking.  Buy the calculator that they're going to be using in their instructions if you can afford it and don't already have another type.
       GuidelinesIf the teachers don't use calculators, or if you're enrolled in a distance course or some other situation prevents your consulting the teachers, here are some guidelines.  Please realize that it's ultimately up to you to make the decision based on what information you collect.  This is only one source of information.  So, the following is a set of guidelines based on the level of math you might be taking.
General Discussion: If you're a real math and calculator geek and money is not a problem, you'd probably be happier with the TI-89. If you are mainly interested in a tool to do your math in the most efficient way, then a TI-83 Silver addition would be entirely sufficient for courses that don't include functions of more than one variable. That unusually comes in second semester calculus. The TI-83 Plus is simple to use and fairly versatile.
   I would point out that it is possible to graph functions of more than one variable on a TI-83, but you have to hold all but one variable constant. For example, if you want to graph e^-(x² +y²), you could replace y² with A, and supply constant values of A from the home screen to get a family of curves. I understand that TI is developing a set of applications that will give the TI-83 Plus some of the capability of the TI-89. If you buy the TI-83 Plus, you get the GraphLink or Connect software  that allows you to download applications from the Internet to your calculator.
   For taking derivatives and integrals of functions of more than one variable, the TI-86 would be suitable and, in my opinion, it's somewhat simpler to use than the TI-89. The last time I checked it was also cheaper.
If you want the ultimate in graphing calculators, then go with the TI-89. As I previously said, if you're not really into calculators, it's going to take quite a lot of studying of the manual to learn to use it.
  And Now:  The following is an attempt to give some idea of what calculator might be needed for a particular set of courses of study. 
      High School:  I don't have contact with high school students, so I don't have a good feel for their needs.  Generally, I would think that if you're not planning to take  Pre-calculus or AP Calculus, a good scientific calculator would be entirely satisfactory.  (FAQ 1 on the Scientific Calculator FAQs is about buying a scientific calculator.)  But be sure to check with some of the teachers to see if they might use graphing calculators for doing graphs is Algebra II.  Incidentally, scientific calculators are sometimes more efficient and easier to use than graphing calculators.
      If you plan to take Pre-calculus or AP Calculus, and especially if you're planning to major in engineering, science, or math in college; then you probably should buy a graphing calculator if the cost is not a problem with you.  A TI-83Plus or a Casio Cfx-9850GB would be sufficient, but I would be remiss if I didn't say that the TI-83Plus is more often the choice among college students.  Be cautious about buying a TI-86 or TI-89.  Although these are excellent for those who have a more than average interest in math, many students never really learn to use these calculators with anything like their potential.
       Developmental Math:  For Basic Math and Beginning Algebra, Elementary Algebra, or whatever your school calls it, you can get by with a good scientific calculator.  Don't buy one of those six-or eight-function calculators.  They're not worth carrying around.  Don't pay more than $14.95 if you're on a tight budget.  See my Scientific Calculator FAQs, FAQ #1,  for more information on buying a scientific calculator.
     For Intermediate Algebra, you may need a graphing calculator depending on whether your school uses one.  In any case, it would be nice to have one to check your answers.  Make your decision based on your major as listed in the categories below.
     Elementary School Teacher, Nursing, Liberal Arts, Communications:    I'm assuming you're going to take College Algebra and either Elementary Calculus or something like Foundations of Mathematics.  Unless you're some kind of calculator guru, don't buy one of the heavy hitters like a TI-89.  Chances are you'll never understand how to use all its power.  Instead, buy a TI-83 Plus or a Casio CFX-9850GB Plus.  You can get by with a TI-82 if you'll enter my program for doing rref and ref on augmented matrices and, for finite math,  the program for doing the simplex method.  Otherwise you're going to be left out when you get to doing augmented matrices or simplex.  The Casio has a program that you'll need to activate for doing rref, or you could use my program for rrefref for the Casio.  That'll give you both ref and rref.  If your teacher is one of those who gives you a lot of augmented matrix work to do by hand, you might find my matrix row operations program helpful for both the TI and the Casio.
    Suppose you absolutely can't afford any graphing calculator.  Hang in there and get you a good scientific for no more than $14.95.  Go to the Tutoring Lab, Learning Center, Academic Assistance Center or whatever your school (community colleges) calls it and use their calculator to do your homework.  They may even have one you can check out and take to do tests. You might also ask your professor about one of the cheaper Casios: FX-7400G Plus or FX-9750 Plus.  I have an older FX-9750, and I worked some with an older FX-7400, but I am not familiar enough with the newer versions of these calculator to give advice on them.  Read my notesbelow on the Durabrand that has recently appeared at Wal-Mart for $1995.
     Economics and Heavy Business Courses:  I'm assuming you'll take Calculus I and Finite Mathematics with some other financial courses.  The finite math may be heavy in linear programming and the Simplex method.  Be sure to find out if your teacher uses one of those special financial calculators in your class.  Otherwise, you can use a TI-83 Plus or a Casio CFX-9850GB Plus.  The Casio has a program called LINPROG that needs to be activated for doing simplex.  You can use my program called LINPRG2 for the TI-83 Plus to do the Simplex method.  Both of these calculators have functions for doing amortization, different types of interest, and other financial functions.
    Chemistry:  You guys probably know what you need.  If you're going to take Calc I and II and no differential equations you probably could get by with a TI-83 Plus or a Casio CFX-9850GB Plus.  If you're going to take higher math, buy one of the heavy hitters like a TI-86 or TI-89.
    Electrical Engineers & Physicists:  You guys know what you need.  If you don't, talk with your professors.  My inclination:  Don't buy one of the simpler graphing calculators.  Buy one of the heavy hitters.  You need the best tools you can get.
    Where to buy:  I'm not going to tell you where to buy; I'm going to tell you some places they're available.  Wal-Mart, Best Buys, Home Depot, Office Depot, Target (I believe Target still has them.), and others that may be specific to your area.  If you want to save money, watch the advertising inserts to your local newspaper about the time the fall semester starts.  Many stores have significant savings at that time.  Call around and see who has the best price. 
    Now, here's something that may seem a little weird to you, but it works for many of the students who come to me and are pressed for money.  I send them to pawn shops.  Many pawn shops in this area have used TI-83 Plus calculators  for $35 to $45 dollars.  I tell the students to make the pawn shop dealer agree to take the calculator back for a couple days or so, until they come in and have me check it out.  You might also try to bargain a little by telling the dealer that the TI-83 Plus is now two versions out of date.  Now, let me give you a little hint on getting a calculator from the pawn shop:  Turn the calculator on; press 2nd, MEM, ENTER.  In the middle of the screen, right below the TI-83Plus will be an entry such as 1.19.  This is the version of the operating system and may tell you  indirectly  how old the calculator is.  (I say may because someone, like me, may have upgraded the operating system.)  The higher the number, the newer, with 1.19 being the highest as of 6/1/06.  If the pawn shop has several calculators, try them all and get the one with the latest version unless you have to pay considerably more. Try to get one with 1.14 or higher.  If you must settle for a lower number, tell the dealer that it's old and he should give you a price break on it.  If you have a friend with Connect or GraphLink installed, you can upgrade the operating system. 
    Now, how about the Durabrand calculator that has recently appeared at Wal-Mart for $19.95?  Here's what little preliminary information I have on it.  (Please read the DISCLAIMER at the start of these FAQs)
    PROS:
     *  Has a 50-key keyboard that appears to be fairly well arranged except, possibly for the SHIFT key.
     *  Has fraction and Ans keys.
     *  Has sufficient memories for most any purpose - 26.
     *  Has about any of the standard algebraic and trig functions that you would want - including one- and two-variable
         statistics.
    *  Algebraic entry of formulas.
    *  Easily obtained battery - CR2032.  This is the same as the battery used for the memory in the TI-83 Plus.
    *  Has some limited programming ability.
CONS:
    *  The display for the graph is very small, 35 x 23 pixels.  The full-screen display on the TI-83 Plus is 62 x 94  and the split-
        screen G-T display is 50 x 46.
   *  As far as I can see, there is no equivalent of the ENTRY function on the TI-83 Plus.  This is very useful when you need to use
       a long expression and only edit a number or maybe two.
   *  Programming is limited to 400 steps divided among ten pre-designated programs.  Gamers, forget about it. 
SUMMARY OF DURABRAND CALC:
        Don't let the small number of cons lead you to believe this is equivalent to the TI-83 Plus or the Casion CFX-9850 series.  This is more on the order of the old Casio 7000G Graphic calculator.  This is merely my opinion, but I'd try to come up with 15 to 20 dollars more money and look hard for a used TI-83 Plus or equivalent. 

-------------------------
(7)  How do I do the rref and ref on a TI-82 calculator as the other people in my class do on their TI-83. 
    There's no quick method for doing Gauss and Gauss-Jordan elimination on the older TI-82 calculators.  At some point TI may include that as a program, but as far as I know, it's not there yet.   Best thing to do, of course :-), is to use my program for doing that.  You'll find it listed in the program descriptions.  It'll take you about 20 to 30 minutes to load it, depending on how familiar you are with programming of TI calculators.
----------------------------------
(8)  How do I graph a circle on the TI-83?
       There are a couple ways to do this, but in any case you must first solve the equation for y. 
Example: 
x2 +y2 =5
y =± √(-x2 +5)
Now, enter the equation, without a leading sign, into the Y1= position.
Now, cursor down to Y2= and enter a negative sign.  That's the (-) sign.
Press VARS, cursor over to Y-VARS, press ENTER, ENTER.  You'll now have -Y1 in the Y2 position.  Press GRAPH.
Your graph won't look like a circle unless you're in ZSquare screen mode.  To get that, press ZOOM, 5.
------------------------
(9)  How do I draw a circle on the TI-83?
       I want to emphasize that drawing is different from graphing.  Drawn graphs cannot be analyzed by any of the CALC functions.  Anyway, to draw a circle with center at (2,4) and radius 7, do the following:
      Preferably deselect the entries in the Y= positions.
      Press 2ND, DRAW, 9.  You'll now have Circle( on your home screen.
      Complete the entry like this: Circle(2,4,7).  Then press ENTER.
      To clear the screen of a Draw or Text entry, select item 1, ClrDraw, from the  DRAW menu.
      I would just add that TI has a very nice conics application for the TI-83 Plus that can be      
     downloaded  for free if you have with the proper software and electronic device.
---------------------------
(10)  How do I put text on a graph?
         
You can do it either from the home screen by specifying the pixels where you want the text placed or you can do it directly on the graph..  The home screen method is the method to use in a program, or, if for some reason, you want to enter text from the home screen.   FAQ 11 will show you how to do that. The easiest way outside a program, I think,  is just to enter text on your graph.  Here's how to do that:
a)  Graph the function that you want the label to appear on.
b)  Press 2nd, DRAW, and scroll down to item 0 and press ENTER.
c)  Using the cursor arrows, move the cursor to the point where you want to start the text.
d)  Press 2nd, ALPHA to lock the ALPHA function in, and start typing in the letters that appear in green on your keyboard.
e)  Remember, if you type number, commas, and other such characters, you'll need to press
the ALPHA key to get the keyboard out of the alphabetic mode. 
------------------------------------
(11)  When I draw text on a graph and use the coordinates that I use for OUTPUT, the text overlaps.  Why?
         You want to remember that the home screen is different from the graphing screen.  The home screen has 8 horizontal rows and 16 vertical columns.  The graphing screen has 62 horizontal rows (pixels) and 94 vertical columns.  I normally use about 7 vertical spaces and 4 horizontal for each letter.
Example:  Let's say I wanted to write SOME TEXT on the screen. Here's how I'd specify it.
Of course, to get to Text(, you press 2nd,  DRAW and select item 0.
Text(1,1,"SOME"
Text(1,21, "TEXT"
If I wanted to write TEXT below SOME, I'd do this:
Text(1,1,"SOME"
Text(1,8,"TEXT"
You can play with the formatting and see what spacing pleases you.
----------------------
(12)  How do I find the inverse of a matrix on the TI-83?
1) First enter the matrix in one of the positions, say matrix [A].
2)  Press 2nd, QUIT to go to the home screen
3)  Press 2nd, MATRIX, 1  (1 selects the matrix A.  If you put the matrix in another location press that number.)
4) Press x-1 .  That's the key on the left side; four keys down.
5) Press ENTER.  Your matrix will be displayed if it has an inverse.  If it has no inverse, you'll get a SINGULAR MAT error.
_________________
(13)  When I enter an equation with large coefficients, I often can't find the graph on my TI-83Plus.  How do I find it?
The TI-83 makes it very simple:  Press ZOOM; then the number 0 to select ZoomFit.  For TI-82 or older TI-83 calculators that might not have the ZoomFit capability, there are different ways you can find the values to set your window.  You could use TRACE and see where the max and min occur.   Another perhaps simpler way is as follows: Press <2nd>, <CALC>,<ENTER>; then enter a negative number for "x" where you'd like to see the graph; then do the same for a positive number.  Set the y-values of your window at approximately these numbers.  Example:  Graph 300x3 -50x +50.  If you follow the steps above and enter -4, you'll get -21070.  For 4, you'll get 17330.  Now, set your window at, say Ymin = -25000 and Ymax = 20000.
--------------------------------
(14)  Is there a way to solve quadratics on a TI-83Plus?
Well, yes there are at least four different ways.  I'll give each a brief description.
Method I:  (Using graph and CALC for real values only.)
a)  Press Y=, and enter your quadratic in the Y1= position.
b)  Press 2nd, [CALC], cursor down to item 2 (zero); then press ENTER.
c)  A screen will appear with "Left Bound," which means for you to move the cursor to the left of the first zero.  Do that, and then press ENTER.  (Rather than use the cursor, you can just enter a number that's slightly to the left of the zero  and press ENTER.)
d)  "Right Bound" will appear.  Do the same thing as above for  the right bound of the first zero.
e)  When "Guess" appears, move the cursor to about where you think the zero is and press ENTER.  (You could also enter a number for this, but I prefer to use the cursor for this value.)
f)  The values for x and y will appear.
Method II: (Using Table.  For real values only.)
a)  Press Y=, and enter your quadratic in the Y1= position.
b)  Press 2nd, [TABLE].
c)  Look for the x-values that correspond to the values for 0 in the Y column.
d)  You may need to change the difference between x-values.  To do that, press 2nd, [WINDOWSET] and change the delta to whatever you want. 
Method III: (Equations Solver.  For real values only.)
a)  Press MATH; 0; ENTER.  ( Item 0 is Solver.)
b)  If the solver is empty, just start entering your equation.  If there's already an equation at the top of the screen, press the up arrow key and enter your equation.
c) Press ALPHA, SOLVE.  Your solution should  appear  after X=.
d)  You can enter a guess for the unknown if you want, but I've found that this sometimes causes the calculator to miss a solution, even if your guess is within four or five units.  Actually, I find solution of quadratics much easier if I first graph them and get a fairly good guess as to what their roots are.  Then I can paste the Y-Var into the equation on the solver and guess the roots fairly accurately.   To past a Y-vars, say Y1, do this:  (You need to be in the equation entry position as indicated above.)
a)  Press VARS; cursor over to Y-VARS; press ENTER.
b)  Select the y-variable where you have the equation entered for  the graph and press ENTER.
c)  The variable you selected will be pasted into the equation position. 
Method IV: (Using the quadratic equation.  For either real or imaginary.)
Actually the best thing for this is to download and enter my little program QUAD, but if you're not into programming, do the following.
a)  Press Y= and enter the part of the quadratic equation with the positive radical into Y9=. (Actually, you can enter the equations in any y-variable, but I like to get them out of the most-frequently-used variables.)
Do that with the following keystrokes: (,  (-), ALPHA, B, +√, (,B,^,2,-,4,, ALPHA, A, ALPHA, C,) )/(, 2,ALPHA, A).   Don't enter the commas.  They're for separation only. When you finish, your entry should look like this: (-B+4AC)/(2A)
b)  Enter  the part of the quadratic equation with the negative radical into Y0=.
NOTE:  If you want to solve a quadratic with imaginary numbers, be sure to go to MODE and highlight a+bi in the seventh line down.
c)  Now, when you want to solve a quadratic, first store the coefficients as follows:
      1)  From the home screen, press the number for the first coefficient; then press STO; then ALPHA, A.
      2)  Follow that same procedure for each variable separating the variables with a colon.  A colon is entered by pressing ALPHA, :. 
d) Now press VARS, cursor over to Y-VARS; press ENTER, then 9; and finally ENTER.
e)  After you have that answer, follow the same procedure as in d), except press 0 instead of 9 in the next to last step. 
---------------------------
(15)  Can I enter fractions and get answers in mixed numbers?
No, the results of multiplication of fractions on the TI-82/83 only gives results in fractions, either proper or improper depending on the answer.  There are some methods, probably considered cumbersome by most students, to enter fractions and get mixed numbers.  Here are a couple examples:
Let's say we want to add 4⅞ + 3⅝.
a)  Enter that as 4 +7/8 +3 + 5/8.
b)  Press ENTER and the answer will be 8.25.
c)  Take 8 as the whole part of the mixed number.
d)  Now to find the fractional part press MATH, cursor to NUM, press 4 (fPart(), 2nd, Ans.
e)  Now press MATH, ENTER.  You should now have this: fPart(Ans
►Frac.
f) Press ENTER and you'll get the fractional part, 1/4.
    Multiplication of fractions is much the same.  If the above problem were multiplication, you'd enter it like this:
    (
4 +7/8) (3 + 5/8).   That would give you 17.671875 and you'd find the fractional part the same was as above.  Division of that problem would, of course, be entered like this: (4 +7/8) /(3 + 5/8).

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(16)  How do I find Sin, Cos, and other trig functions?   I keep getting answers that don't make sense.
  The most common problem that students have is having the Radian/Degree mode set in Radian when they're entering degrees.  To change that press MODE, press the down arrow to move to Radian; then the right arrow to Degree; then press ENTER and  CLEAR.
   After you're all set up on the MODE, just press the function you want and enter the degrees. 
Example: Find Cos 45
  Press COS; then enter 45.  At that point you'll have cos(45; then press ENTER, and you'll get .707106....  There's no need to close parentheses unless you have something following that might be mistaken for part of the argument of the trig function. 
---------------------------
(17)  Can I store pictures/graphs that I have made/drawn on my screen?
Yes, you can store up to 10 graph/pictures by using StorePic.  Assume you want to store the "picture" in Pic 1. 
a)  With the graph displayed press 2nd, [DRAW] and cursor over to STO and select item 1, StorePic.  Press ENTER, and StorePic will be pasted to the home screen. 
b)  Enter the number for the storage location where you want the picture stored.  If you enter 1 it will be stored in location Pic 1; 2 for Pic 2, etc.  Press ENTER. 
c)  Remember, that to store another picture or to recall a picture, you must clear the screen.  You do that by pressing 2nd, [DRAW] and selecting item 1, ClrDraw;  then pressing ENTER. 
    I would suggest that, to keep your memory usage to a minimum, you clear the drawings from the Pic locations after you're finished with them.  Here's how to do that:
a)  Press2nd, [MEM], select item 2 and press [ENTER]
b)  Select item 8, Pic, and press [ENTER].  Delete the items you want to delete with the [DEL] key.  Press 2nd, [QUIT] where you're finished. 
--------------------------
(18)  Is there a way to solve an equation on  the TI-83Plus without graphing?
Yes, you can use  the Solver to solve equations with real solutions..  Here's how to do it:
a)  Press MATH; 0; ENTER.  ( Item 0 is Solver.)
b)  If the solver is empty, just start entering your equation.  If there's already an equation at the top of the screen, press the up arrow key and enter your equation.
c) Press ALPHA, SOLVE.  Your solution should  appear  after X=.
d)  You can enter a guess for the unknown if you want, but I've found that this sometimes causes the calculator to miss a solution, even if your guess is within four or five units.  Actually, I find solution of quadratics much easier if I first graph them and get a fairly good guess as to what their roots are.  Then I can paste the Y-Var into the equation on the solver and guess the roots fairly accurately.   To past a Y-vars, say Y1, do this:  (You need to be in the equation entry position as indicated above.)
a)  Press VARS; cursor over to Y-VARS; press ENTER.
b)  Select the y-variable where you have the equation entered for  the graph and press ENTER.
c)  The variable you selected will be pasted into the equation position.
---------------------------
(19)  How do I enter a matrix in a TI-83?
a)  Press 2nd, MATIX, and cursor over to EDIT and press ENTER.
b)  Enter the number of rows; press ENTER; enter the number of columns and press ENTER.
c)  Now enter the numbers  in the matrix, pressing ENTER after each entry.   Do this until you have all of the numbers entered.  (Note:  Do not just skip over a number that's already in the matrix.  It may be a calculated number and may be just a bit less accurate than an entered number.)  To get out of matrix edit, press 2nd, QUIT.
---------------------------
(20)  How do I solve a system of equations on the TI-83Plus?
a)  First enter the augmented matrix in one of the matrix positions, say [A],  as described in item (19) above.
b)  After you have the matrix entered, press 2nd, QUIT to get out of matrix edit.
c)  Press 2nd, MATRIX, cursor over to MATH, and cursor down to item B,:rref(.
d)  Press ENTER.  You will now have rref( pasted to the home screen.  Now you want to paste matrix A to the home screen.   So, press 2nd, MATRIX, and press ENTER.
e)  You will now have rref([A] pasted to your home screen.  If you want the answer in fractions, skip to the  next item, item f).
     If you want the answer in deciamals, press ENTER and the solution will appear.
f)  To obtain the answer in fractions press MATH, ENTER, ENTER and the answer will be displayed.
---------------------
(21)  How do I do matrix row operations with the TI-83Plus?
Let's say that you have this set of equations:
x +2y +3z = 4
2x - y - 2z = 0
x-  3y - 3z = -2
So that, you have this augmented matrix:
[ 1  2   3   4
   2 -1  -2   0
   1 -3  -3   -2]
Now, you want to multiply row 1 by -2 and add it to row 2.  I'll use "shorthand" such as -2R1 + R2=>R2, to indicate this type of operation. 
a)  So, enter the matrix as in Item (19) above; then press 2nd, QUIT to go to the home screen.
b)  From the home screen, press 2nd, MATRIX; scroll over to MATH; scroll down to item F, and press ENTER.  You should now have *row+( on your home screen.
c)  Now you want to enter the multiplier, letter of the matrix, row number multiplied by, row number to replace in that order.  Do this:  Enter -2, press the comma button, press 2nd, MATRIX, ENTER.  You should now have *row+(-2, [A] on your screen.  DO NOT enter [A] with the brackets and the letter A.
d)  Now press the comma button, enter 1;  press the comma button and enter 2.  You should now have *row+(-2,[A],1,2 on your screen.
e)  Press STO, 2nd, MATRIX, ENTER. 
f)  You should now have *row+(-2,[A], 1,2►[A] on your screen.  DO NOT enter [A] with the brackets and the letter A.  (Note carefully that if you don't add the STO, [A], then matrix A will not be changed in your calculator.   Also notice that you can either close the parentheses after the last row number or leave them open.)
g)  To get a zero in column 1 of the 3rd row, enter this:  *row+(-1,[A],1,3►[A].
h)  You now have this matrix:
[ 1  2   3   4
   0 -5  -7  -8
   0 -5  -6   -6
i)  Now enter this:  *row+(-1,[A], 2,3►[A]. Note that instead of re-entering all of these, you can just press 2nd, ENTER, and then edit the entry that appears for the proper multiplier and row numbers.
j)  Now, multiply row 2 by -1/5 as follows: 
*row(-1/5,[A],2►[A].
k)  If you want to add two rows; then the syntax is this: row+(matrix letter, row to be added, row to be replaced)►[A]
l)  To swap rows, use this syntax:  rowSwap(matrix letter, first row, second row►[A]
-------------------------------
(22)  How do I find  the angle whose cos is 0.5?
First make sure that your calculator is set for radians or degrees, whichever you want the answer in. (Usually you'll want it in degrees.)  To change the mode, do this:
a)  Press MODE; then cursor down to the line with Radian and   Degree.  Select the one you want and press ENTER.  Press CLEAR  to get back to the home screen.  Now to find  COS-1 0.5, just press 2nd, press the COS button; then enter the argument 0.5  and press ENTER.
-------------------------------------
(23)  How do I transfer a program from one TI-83 Plus to another TI-83 Plus?
I'll assume both are TI-83 Plus.
1) Turn both calculators off and plug in the unit-to-unit cable in both calculators.
2) Turn on both calculators and Press 2nd, LINK on both. Cursor over to RECEIVE
on the RECEIVE calculator, the calculator that you're transferring the program to.
3) Press ENTER on the Receive calculator. The word "Waiting"  should appear.
4) On the sending calculator, cursor down to Prgm and press ENTER.
5) Cursor down to the program you want to transfer and press ENTER. The program that you selected will be marked with a square "dot."
6) Cursor over to TRANSMIT press ENTER.
If everything is connected satisfactorily, transmission of the program should start. Otherwise, you'll get a transmit error after a few seconds.
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(24)  Can I find the fractional equivalent for values such as Intersection and Zero?
You can if the decimals are rational numbers.  As an example, suppose we've graphed y = x+5 and y = 4x + 10 and found the intersection at x=-1.666667, y = 3.3333333.  Here's how to find the fractional equivalent. (The answer is obvious, but this is a simple example.)
a)  Press 2nd, [QUIT] to go to the home screen.
b)  Press [x,T,0,n]; then MATH; ENTER; ENTER.  The fractional equivalent of x, -5/3,  will be displayed.
c)  Press [ALPHA], Y, MATH, ENTER, ENTER.  The fractional equivalent of y,  10/3, will be displayed.
---------------------------------
(25)  Can I graph inequalities on the TI-83Plus?
Well, yes, but it's not really just straight forward graphing.  Let's assume a couple of simple equations such as x + y
≤4 and x-y ≤ 2.  
a)  First solve each equation for "
y," getting the following: y ≤ -x +4 and  y ≥x-2.  (Be sure you don't just change the inequalities to equations and solve for y.)
Now, do the graphing as follows:
 b)  Press Y= and enter the first equation as Y1 and the second as Y2. 
c)  Now you want to set the shading.  So, go to the Y1= and cursor over to the extreme left where you'll see a flashing design.  Press ENTER repeatedly until you see a filled-in, right triangle with it's right angle on the left bottom.  That's the < shading. 
d)  Now go to Y2= and do the same thing except that you want to select the triangle that is flipped over from the one you selected above.  .
e)  Press GRAPH, and you'll see the shaded regions. 
Remember to change the shading back to a regular line to graph equations. 

A second method that I find somewhat less time consuming.
Let's say we have this equation: x2 -x-12 >3.
1)  Enter the left side of the inequality in Y1= and the right side in Y2=.
2)  In Y3 enter Y1 > Y2 as follows:  Press VARS, cursor to Y-VARS, ENTER, ENTER.
3)  Press 2nd, TEST, 3.
4)  Press VARS, cursor to Y-VARS, ENTER, 2.
5)  Press GRAPH and your display will show both graphs and the graph of where the inequality is true.  You can disable the individual graphs if you feel the display is too cluttered.
____________________
(26) How do I set up the domain for a function on a TI-83?
This is pretty much like graphing piecewise functions.  So, if you'll read FAQ (4), that'll solve most of your problems.  There's just one thing I'd add to that:  In the case of a function like cos(x) over the domain (- Π/2, Π/2) you'll get a slightly nicer graph if you multiply by the limits rather than divide by them.  In other words, you would enter this:  cos(x)(x≥-Π/2)(xΠ/2).  That way, the graph will return to zero at the end of the ranges.
____________________________
(27)  How do I graph the residuals after I do a linear regression?
First you want to  calculate the residuals.  So, if you'll follow FAQ (5 ) above,  that'll solve that problem for you.  A few of the parameters such as the window may be different, but it's basically the same.  Now, you want to get the residuals into L3 in the table.
a)  Press [STAT], [1] and that'll take you to the List table.  Cursor over  and up so that that the L3 over the L3 column is highlighted. 
b)  Press [2nd], [INS].   Names= is displayed at the bottom of the screen.
c)  Press[2nd], [LIST] and cursor down to RESID.  Press [ENTER] and the values are stored in column L3.
d)  Press [Y=] and make sure that none of the Y-variables or Plot functions are enabled (highlighted). 
e)  Press [2nd], [STAT PLOT] and select Plot 1.  Highlight ON by cursoring there and pressing [ENTER].
f)  Leave L1 in XList, but change Ylist to RESID by entering those letters with the ALPHA key.
g)  Press ZOOM 9 and you should have a scatter plot of the residuals.
_________________________________
(28)  How do I generate random numbers on a TI-83/TI-83 Plus?
1)  Press [MATH]; cursor to PRB and press [ENTER]. rand will be pasted to the home screen.
2)  If you only want one number between 0 and 1, press [ENTER].
3)  If you want more than one number between 0 and 1, add the number you want in parentheses. Example:  rand(5), for 5 random numbers.
4)  If you want five numbers between 0 and 10, your entry will look like this: rand(5)*10.
5)  If you want five numbers between 0 and 50, your entry would look like this: rand(5)*50.
6)  If you want integers only, do this:  Press [MATH], cursor to PRB, scroll to rantInt( and press [ENTER]. 
7)  randInt( will be posted to the screen.  Now enter the numbers so your entry looks like this:  randInt(0, 50, 5).
_____________________
(29)  How do I store random numbers in a list and arrange them in order?
1)  To generate the numbers, follow the method in (28) above. 
2)  To store the numbers, follow your entry by [STO], and the list name, for example, L1.  If you want to store ten random numbers in list L1, your entry will look like this:  rand(10)-->L1.  The arrow is generated by pressing [STO]. 
3)  To sort the numbers in L1, Press [STAT]; select item 2 or 3 depending on how you want the numbers sorted; then press [ENTER].  SortA( will be pasted to the home screen if you selected item 2.
4)  Press [2nd], L1, [ENTER].  You'll get the "Done" response, indicating  the numbers are sorted.
=================
(30)  How do I calculate IRR on an investment?
Let's say you invest $500 initially and your cash flows for years 1 through 4 are as follows: $150, $200, $250, and $250.  Find IRR as follows:
1)  From the home screen, press [STAT], [ENTER]; then enter the values consecutively in list L1.
2)   Press [2nd], [QUIT] to go to the home screen.
3)  Press [APPS]; then [ENTER]; then 8 to paste irr(  to the home screen.
4)  Enter items so that the entry on the home screen looks like this:  irr(-500, L1). 
5)  Press ENTER and after a couple  seconds you'll get 22.77....
==========================
(31)  How do I do a regression and graph the scatter plot and the regression equation on the same axis?
First you need to get your data into lists.
 Press [STAT], [ENTER]
Then enter the data-point numbers ( the x-values)  in L1 and the corresponding values (y-values)  in L2.
Press [2nd], [QUIT]
To do the scatter plot do this:
1)  Press [2nd], [STAT PLOT] and press [ENTER] to turn Plot 1 on.
2)  Cursor to the scatter diagram on Type and press [ENTER] to highlight the scatter diagram.
3)  Enter L1 in the Xlist, and L2 in the Ylist; the select the type marker you prefer.  (I like a + ).
4)  Press [ZOOM], 9  and the scatter plot will appear on the screen. (Alternatively, you could press GRAPH and set the window as you choose.)
Now to set up the regression:
5)  Press [STAT], cursor to CALC, and press the number to the left of the type regression that you want.  For example, press 4 for Linear.
6)  LinReg(ax+b) will appear on the screen if you pressed 4 in item 5 above.  If you have your data in the default lists, L1 and L2, you can skip the rest of  this step and go directly to step 7.  Immediately after that enter the following: [2nd], [L3] [,], [2nd], [L4], [, ]  .Note that the commas outside the brackets are just separators so you can tell what I'm doing. They do not appear in the syntax.
7)  Now, you want to store this as a Y-variable, say, Y1. So, do it this:
 Press [VARS], cursor to Y-VARS, [ENTER], [ENTER]
8)  If you pressed 4, you should now have this on your screen.  LinReg(ax+b) L3, L4, Y1.  Note if you had your data in the default lists, you will have LinReg(ax+b) Y1.
Press [ENTER].  After a few seconds a long equation with coefficients having several decimal places will appear on the screen.
9)  Press [GRAPH] and both the scatter plot and the graph of the regression equation will appear on your graph screen. 
10)  To predict the y-value for an x-value not in the data first press VARS, cursor to Y-VARS, press 1, 1.  Y1 will then be pasted to the home screen. 
11)  Enter the x-value of your choice in parentheses after Y1.  Example:  Y1(12)
12  Press ENTER and the y-value corresponding to the  x-value of 12 will appear.
13)   (NOTE:  After you've finished with the regression, cursor to Plot1 on the graphing screen and press ENTER to remove the highlight.  Otherwise, you'll plot the scatter plot every time you do a function graph.)
===========================
(32)  The TI-83 Plus selects the number of classes when I do a histogram.  Is there any way I can choose my own?
Well, yes, but you'll need to do  a little work.  Here's how to do it.
1)  Enter your  data List L1.. 
If your data is not in order, you can simplify the next steps by sorting the data. Sort it by pressing STAT, selecting SortA( or SortD( as appropriate, then entering the list name of the data (often L1)   As an example, you might have this displayed on your screen: SortA(L1..  Now, press ENTER, and your data will be sorted.
2)  Now, from the sorted data, determine the class width and lower boundary of the lowest class.
Now do this:
3)  Press [2nd], [STAT PLOT], highlight 1, and press [ENTER].
4)  Highlight ON on the next screen; then highlight the histogram symbol.  Make sure L1 is entered for the Xlist and use the default,1, for Freq. (Note Freq would be the list name for the Freq list is you had "tabled" data.) 
5)  Press [WINDOW],  and enter the lower boundary of the lowest class as Xmin  and your chosen class width as Xscl.
6)  Press [GRAPH].  You can use {TRACE] to display the value and boundaries of a particular bar on the histogram.
===========================
(33)  Do I really need to change the batteries on my TI-83+ when I upgrade the operating system?
Oh, absolutely.  I would definitely do it. The OS is stored in flash ROM.  The way flash ROM works is that when you want to store a logic 1,  a voltage is applied that causes so-called hot electron to jump the band gap between the semiconductor and gate insulator and get trapped as charge in the gate insulator.  I don't know what type circuit TI uses to do  this, but it stands to reason that the amount of charge stored in the insulator will be proportional to the battery voltage. The greater the  trapped charge the  "harder on" the transistor will be  and, therefore, the the lower the drain-to-source resistance.  So, I some of the things you might expect form fresh batteries are the following:  
1)  The upgrade will probably go faster because the higher voltage of a new battery will charge the stray capacitances inside the circuitry faster. 
2)  Flash memory will have higher logic levels stored on their cells providing a more definite logic level for the sense amplifier. That would improve  immunity resulting in fewer  transfer errors. 
3)  The charge on the cells might also last a little longer in case you happen to have a slightly leaky cell.
That's probably more than you ever wanted to know on that subject, so enough.  The way I do the upgrade  is to keep a set of new batteries on hand, and when I upgrade a student's calc, I put in the new batteries.  Then when the upgrade is finished, I reinstall the student's older batteries.
===========================
(34)  Does the conics application for the TI-83 Plus  provide the same graphing capability as the  graphing functions that are built into the calculator? 
Not exactly. The conics application is more like a draw function than a graph function.  The [TABLE], [CALC], [WINDOW], and other functions will not work with the conics app.  The [TRACE] will work, however, and you can use that to get values off your graph in case you're required to put it on paper.   If you're wondering about whether to get it, I recommend you get it.  It's free, and it's better than solving for "y"  and entering two equations in most cases.
===========================
(35)  I've read various places on the Internet that there's not much difference between the TI-83+ and the TI-82.  Is that correct?
Well, it depends on the perspective you have.  From the perspective of the student taking college algebra or pre-calculus, there are  a couple important differences.  Here are a few differences that I'm aware of:
1)  Probably the most important from the  perspective I mentioned is the inability of the TI-82 to solve augmented matrices and display them in either reduced row-echelon or row-echelon form.  That's why I wrote my program REFRREF, incidentally.  That will give the TI-82 that capability.
2)  Next, I would say,  is the inability of the TI-82 to handle complex numbers.  That also prevents students from using certain programs that include imaginary number solutions.
3)  Next is the inability of the TI-82 to handle the Conics application that takes the hassle out of graphing conics.  
4)  I'll now list several items that are of various degrees of importance, depending on how extensively your teacher uses the graphing calculator in his/her teaching:  Graph formats (solid line, dotted line, etc.); interactive equation solver; and other things such as gcd, lcm. 
If you already have a TI-82, you can get by okay if you'll install programs, mine or others of your choosing, for doing augmented matrices and imaginary numbers.  But if you have yet to buy a calc and have the money, I'd suggest either the TI-83+ or the TI-83+ Silver Edition.
_____________________
(36)  Is it possible to do a stem-and-leaf chart on the TI-83 Plus?
Well, sort of.  Let's say you have the numbers 41, 54, 67, 53, 46, 58, 63, 62, 71, 83, 74, and 86.  Do the following:
1) Press [STAT], [ENTER].   Enter the data into L1, and press [2nd], [QUIT].
2)  Press [STAT], cursor to item 2 and press [ENTER].
3)  Press [2nd], [ENTER] and enter the stem data in L2  and the leaf data in L3. 
4)  Press [2nd], [STAT Plot], [ENTER].
5)  Turn Plot 1 ON, highlight the first type graph, enter L2 in the Xlist and L3 in the Ylist.  Select the type mark you prefer.  ( I like the + sign.)
6)  Press [WINDOW] and set Xmin = 0, Xmax = 9, Ymin = 0, and ymax = 9.
7)  Press [GRAPH].
If you want, you could press [2nd], [FORMAT], and highlight the GridOn.   Then press [GRAPH].  If you don't like the result, turn the resulting grid off. 
----------------------------------------
(37)  How do I find the critical numbers for y = x3 -x2 -3x +1 on my TI-83 Plus?
1)  First press [Y=] and enter the equation in the space opposite Y1=,  and press [GRAPH] to graph the equation.
2)  Press [2nd], [CALC],  press 4 (maximum).
3)  Move the cursor slightly to the left of the peak of the curve at approximately x = -.7 and press [ENTER]; then move the cursor to the right of that peak and press [ENTER].  Finally, move it to the center of the peak, and press [ENTER] again.
4)  The value at x = -0.7207 should appear for x.
5)  For the minimum, repeat the above except select 3 (minimum) in step 2.
Incidentally, if you have places where the derivative does not exist, you can approximate the value by using pressing [2nd], [TRACE], and moving the cursor  almost to the asymptote or discontinuity. 
-------------------------------------
(38)  On my TI-82,  when I enter (-32)^(1/5); then (-2)^3 I get a correct answer, -8, but when I enter (-32)^(3/5) I get Ma ERROR.  Why?
It's probably because of the algorithm used in the last case.  The way most scientific calculators, the TI-82, and the CFX-9850 does x^m/n is with the identity em/n*ln (x) .  As you can see, when you have -32, you have the natural log of a negative number.  That's a complex number and so is listed as an error.  Incidentally, the TI-83 Plus handles all of these exponentials with no problem. For more on this topic, see item 13 on the FAQs for Scientific Calculators
-----------------------------
(39)  My teacher says the TI-83Plus is useless for finding the derivative.  Why is that?
  
Well, I would be a little more charitable and say you need to be aware of its limitations.  First of all, you need to realize that the TI-83/Plus calculators will not give you an expression for the derivative.  That is, it won't give you 2x for the derivative of x2.   What it will do is give you a number for the value of the derivative  at a particular point, say x = 2.  But again, you need to be aware of it's limitations.           Because the TI-83/Plus uses the symmetric difference method of evaluating the derivative, it will sometimes give you a value when the derivative does not exist at a  cusp or when the denominator is zero.  Here are a couple examples:  derivatives of f(x)=|x| evaluated at zero; f(x) =x1/3 evaluated at zero.  If you're dealing with a suspicious derivative, back off the evaluation point about .01 or so, and if you get a considerably different value, then the first value is probably wrong.  For example, nDeriv of f(x) = |x| evaluated at .01 is 1 rather than zero for the value given for  x=0, and nDeriv of f(x) = x1/3 at .01 is 7.19 rather than 100 at give for zero.  It's not a bad idea to graph a function to  alert yourself  to possible pitfalls.
_______________
(40)  Can I draw points on the graph screen on my TI-83Plus?
Yes, but I want to emphasize that drawing is different from plotting.  To draw a point from the graphing screen, do this:
1)  It's probably best to set the window to ZDecimal.
2)  Press 2nd, DRAW.  That will take you to the graphing screen with the cursor displayed.
3)  Using the cursors arrows, move the cursors to the point you want as indicated by X= and Y=; then press ENTER.  Your point will be on the screen.
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Last Revised: 2/20/07.

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