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How to find 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 find answers. After you've located the FAQ number that you want, just use the Find and enter the index number enclosed in parentheses.  The start point for the search should be below the listing in the index.

(1)  How do I graph a piecewise function on a Casio CFX-9850GP Plus?
(2)  How do I do the rref and ref on a Casio CFX-9850GB Plus calculator as the other people in my class do on their TI-83?
(3)  What's the best graphing calculator to buy, and where's the best place to buy one?
(4)  How do I find the inverse of a matrix on the Casio CFX-9850/Plus?
(5)  How do I activate the program ROWREDA to do Gauss-Jordan?
(6)  When I enter an equation with large coefficients, I often can't find the graph on my CFX-9850Plus.  How do I find it?
(7)  How do I graph a circle on the CFX-9850Plus?
(8)  How do I draw a circle on a graph?
(9)  How do I find what the angle whose cos is 0.5?
(10)  How do I transfer a program from one Casio CFX-9850 Plus to another?
(11)  How do I graph an inequality on the CFX-9850+ and do the shading?
(12)  How do I  find the derivative on my Casio CFX-9850GB Plus?
(13)  Is there a way to solve quadratics on a CFX-9850Plus?
(14)  How do I solve a system of equations on the CFX-9850Plus?
(15)  How do I do matrix row operations with the CFX-9850Plus?
(16) How do I set up the domain for a function on a CFX-9850Plus?
(17)  How do I graph a linear regression on the CFX-9850+?
(18)  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?
(19)  Isn't there a way to edit entries on the CFX-9850 the way my friends use ENTRY on the TI-83 Plus?
(20)  My CFX-9850 won't scroll past the certain number is a table.  How can I fix that?


DISCLAIMER:  The FAQs on this web site, and especially FAQ #3,  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.

(1)  How do I graph a piecewise function on a Casio CFX-9850BG Plus?
Doing this on the Casio is very straightforward.
Let's say we have this piecewise function to graph:
3x-2 { -5<x<0
x +1 { 0<x<5
The in the Y= graphing list, type this:
Y1= 3x-1, [-5,0]
Y2=x+1, [0, 5]
Press [F6] and that's all there is to it.

(2)  How do I do the rref and ref  on a Casio CFX-9850GB Plus calculator as the other people in my class do on their TI-83.
     There are several approaches you can take.  I would, of course,  recommend my program casrefrref.:-)  You can do either ref and rref by selecting the appropriate one from the menu. 
     Suppose you're only spending a lecture or so on matrices and don't want to take the 20 minutes or so to enter my program.  The next best thing is to activate a program called ROWREDA that is already stored in the Casio memory, but is not active..  To learn how to activate that program, go to my program casrefrref that can be referenced from  the index page.  The program ROWREDA will not give you the ref form but will give you the rref form.
     Finally, you can solve the equations and make up your own rref matrix by hand.  To do that for rref (won't work for ref) you can solve the equations using  EQUA from the icon menu.  Then set up a matrix on a sheet of paper that has the same dimensions as the one you solved.  Fill in the diagonal with 1s and the last column with the answers you got with the EQUA function.  Fill in all other positions with 0s.
    You can do ref using the row operations capability of the calculator.  That's beyond the scope of this short description, and many students in the college algebra and elementary calc level of math find it a tedious process.  If you're an engineer or science major, it should be no problem. 

(3)  What's the best graphing calculator to buy, and where's the best place to buy one.
  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 by clicking Webmaster in the navigation bar.

 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)
     *  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
    *  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.
    *  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. 
        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. 

(4)  How do I find the inverse of a matrix on the Casio CFX-9850/Plus?
a) First enter the matrix in one of the positions, say matrix A.
b)  Press MENU.  Then select the RUN icon, and press EXE.  That'll take you to the home screen.
c)  Press OPTN, F2; then F1.  Mat will appear on the home screen. 
d)  Enter the letter of the matrix you want by using the ALPHA function and letter keys.
e) Press SHIFT; then x-1 .  x-1 is the  key in the fourth row; fourth column. 
f) Press EXE.  Your matrix will be displayed if it has an inverse.  If it has no inverse, you'll get a Mat Error. 

(5)  How do I activate the program ROWREDA to do Gauss-Jordan?
a)  First select the icon PRGM and press EXE.
b)  Press F6; then F5(Load).
c)  Scroll down to USA, press EXE, then scroll down to ROWREDA and press EXE.
d)  The message "Load Completed" appears soon.
(6)  When I enter an equation with large coefficients, I often can't find the graph on my Casio CFX-9850Plus.  How do I find it?
(7)  How do I graph a circle on the CFX-9850Plus?
a) Go to the MENU, select CONICS, and press EXE.
b)  Scroll down to the diagram of a circle and press EXE.
c)  Enter the x-coordinate of the center for H; y-coordinate for K; and the radius for R.
d) Press F6, DRAW.
Notice that your circle will not appear circular unless you have the proper window setup.  To get the proper setup, press SHIFT, ZOOM, F6,F2(SQR).  If the circle is too small, press SHIFT, ZOOM,F5(AUTO).
(8) How do I draw a circle on a graph?
Well, it's easy to graph a circle with the CFX-9850Plus, but here's how to SKETCH one.
a)  From the graph screen, press SHIFT, F4 (SKETCH).
b)  Press F6; then F3(Crcl).
c)  Move the cursor to the point where you want to center of the circle to appear and press EXE..
d)  Now move the cursor out to the length of the radius and press EXE.  A circle will appear. 
To clear sketches, press SHIFT; SKETCH; F1.
(9)  How do I find what 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 SHIFT, SETUP; then cursor down to Angle and press F1, F2 or F3, whichever one you want.  Press EXIT to get back to the home screen (RUN screen).  Now to find  COS-1 0.5, just press SHIFT, press the COS button; then enter the argument 0.5 and press = or EXE.
(10)  How do I transfer a program from one Casio CFX-9850 Plus to another?
a)  Insure that the power is off on both calculators and plug one end of the SB-62 unit-to-unit cable into each calculator.
b)  From the main menu page, select the LINK icon and press EXE.
c)  Press F2, RECEIVE, on the receive calculator.  Note that you must send data within six minutes or an error occurs.  You can press AC to cancel the transmit.
d)  On the transmit calculator, press F1, Transmit; then F1, Select.
e)   Scroll down to the program you want to transfer and press F6.  You'll get a Yes or No to confirm transmit.  Press F1, Yes.  Transfer will begin.  If there's a problem, you will get a Transmit ERROR!  Press AC to clear the error.  Press MENU to get back to the menu screen. 
(11)  How do I graph an inequality on the CFX-9850+ and do the shading?
a)  First, solve the inequalities for y. (Be sure to solve the inequalities, not the equations. 
b)  Select the GRAPH icon and press EXE.  If a graph is shown, press F6 to go to the Y= Screen.
c)  Press F3 (Type), and then F6 to go to the inequalities. 
d)  Select the applicable inequality and press its corresponding "F" key. 
e)  Enter the inequality expression and press EXE to store.
f)  Press F6, DRAW,  to graph.
(12)  How do I  find the derivative on my Casio CFX-9850GB Plus?
First check the SET-UP to make sure you have the derivative turned on.  You can do that as follows:
a)  Press [2nd], [SET-UP]; then scroll down to derivative.  If On is shown, don't do anything. If On is not shown, press F1.  
Secondly, the derivative works with Trace, so you'll need to press [2nd], [Trace] to get a readout of the derivative as you move along the function curve.
(13)  Is there a way to solve quadratics on a CFX-9850Plus?
a) Highlight the EQUA icon on the menu. Press [EXE].
b)  Press F2 (POLY); then press F1 for degree 2.
c)  Enter the coefficients and press F1 (SOLVE).  The solution will appear as a 1x2 Matrix.
As an aside, cubic equations can be solved similarly.

(14)  How do I solve a system of equations on the TI-83Plus?
a)  Highlight the EQUA icon on the menu and press [EXE].
b)  Select the maximum number of unknowns by pressing the appropriate "F" key..
c)  Enter the coefficients of the equations and press F1 (SOLV).
(15)  How do I do matrix row operations with the CFX-9850Plus?
It's pretty straight forward on this calculator.
a)  Highlight  the MAT icon from Menu and press [EXE].
b)  Enter the dimensions of your matrix, press [EXE], and enter the numbers for your matrix.
c)  Press F1 (R-OP) and select the type operation you want to perform. Numbers should be entered in the order of multiplier, row number being multiplied, row being added to, as appropriate.
(16) How do I set up the domain for a function on a CFX-9850Plus?
Setting the domain is very straight forward.  Say, you want to graph 3x-1 from -5 to 0.  Enter this in variable Y1 in
a)  3x-1, [-5,0].  Then press [EXE], F6.  That's all there is to it.
(17)  How do I graph a linear regression on the CFX-9850+?
a)  Highlight the STAT icon and press [EXE].
b)  Enter the x-data in List 1 and the y-data in List 2.
c)  Press F6 (SET), and scroll down to Graph Type and press F1(Scat) if it's not already set.  Set up the other choices such as List1 for XList and List2 for YList.
d)  Press [EXE]; then F1 (grph1).  That'll do the scatter plot.
e)  Press F1 (X).  That'll give you a, b, r , and r2.
f)  Press F6 (Draw), and that'll draw the best line.
(18)   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.  For more on this topic, see item 13 on the FAQs for Scientific Calculators

(19)  Isn't there a way to edit entries on the CFX-9850 the way my friends use ENTRY on the TI-83 Plus?
As a matter of fact, yes.  Although it's not quite like  the TI-83 Plus.  Let's say you've entered several calculations and you want to edit the last one.  Press the left cursor if want to start editing at the end of the expression or the right cursor if you want to start at the beginning. 
      Now, suppose you have entered three expressions, and you want to go back and edit the first one.
         a)  Press AC.  All of the expressions are cleared from the screen, but don't panic.  They are all stored in memory.
         b)  Press the up arrow and the expressions and will appear in inverse  sequence as the up-arrow is pressed

(20)  My CFX-9850 won't scroll past certain numbers in a table.  How can I fix that?
       Students often notice this when they're working with someone who has a TI-83 Plus, which will scroll past the limits set in the table.  The CFX-9850 won't do that.  One way to compensate for that is to set the RANGE very wide, say -15 and 15 and just leave it there.  When you're in the graphing mode, you might find it convenient to just use the TRACE function.  Do that as follows:
        a)  Press SHIFT, ZOOM and press F6 if INTG is not displayed. 
        b)  Press F4 (INTG); then press SHIFT, F1(TRACE), and you can use the cursor to scroll through different x-values.

Released:  3/17/04
Last Revised: 3/31/07