Casio fx-991EX Classwiz Tips: Tables and Graphs

Casio fx-991EX Classwiz Tips:  Tables and Graphs

This week I am going to show some things that can be done with the Casio fx-991EX Classwiz.  

Believe it or not, the Classwiz can produce graphs of functions.   But not in the way we are used to.  

Generating Tables and Graphs

To generate a table, press [ MENU ], 9: Table.  The Classwiz will always ask for two functions f(x) and g(x).  The function g(x) can be left blank.

You are asked for:

Start:  minimum x value

End:  maximum x value

Step:  change of x

number of steps =  ceiling((End - Start) / Step)

The maximum number of steps for f(x) alone is 45, it gets reduced to 30 if both f(x) and g(x) are used. 

The table of values are displayed.

While the table is displayed, you can generate a graph by pressing [SHIFT] (QR).  This has the Classwiz generating a QR code.  You will need a QR reader, which you can use the Casio EDU app to read the code.

Once the QR code fits into the camera, you are given a link.  Below are examples of graphs:

I hope this week has been helpful in highlighting some of the features of the Casio Classwiz.   For the students in school, I wish you a happy and successful school year.

The next blog post will be on September 15, 2022.   Also, I am going to talk about HHC 2022 in Nashville.  

Eddie

All original content copyright, © 2011-2022.  Edward Shore.   Unauthorized use and/or unauthorized distribution for commercial purposes without express and written permission from the author is strictly prohibited.  This blog entry may be distributed for noncommercial purposes, provided that full credit is given to the author. 

Casio fx-991EX Classwiz Tips: Normal Distribution

Casio fx-991EX Classwiz Tips:  Normal Distribution

This week I am going to show some things that can be done with the Casio fx-991EX Classwiz.  

The Normal Distribution 

The Classwiz's Distribution mode has calculations for the following probability distributions:

1.  Normal, f(x) = exp(-1/2 * ((x - μ) / σ)^2 ) / (σ * √(2 * π))

2.  Binomial

3.  Poisson

This is Mode 7.

Normal CD - Finding the Area

[ MENU ], 7: Distribution, 2: Normal CD

The CDF function calculates the area (probability) between two limits.   The lower and upper tail areas require the limits to be -∞ and +∞, respectively.  However, the Classwiz does not provide values for -∞ and +∞.  For the best estimate, I suggest using -7 and 7 are the limits.  The calculator calculates the probability from -7 to 7 to be 1.

Example:

(For all the examples, the standard values μ = 0, σ = 1)

Lower tail area to x = 3:  lower limit = -7, upper limit = 3; area:  0.9986501019

Lower limit = -2, upper limit = 2; area:  0.954499736

Upper tail from x = -1:  lower limit = 1, upper limit = 7; area:  0.1586552539

Inverse CD

[ MENU ], 7: Distribution, 3: Inverse Normal

This calculation gets the point value for a lower tail distribution (-∞ to x).

Example:

(For all the examples, the standard values μ = 0, σ = 1)

Area = 0.5; xInv:  0

Area = 0.6; xInv: 0.2533470931

Area = 0.7; xInv: 0.5244004382

Eddie

All original content copyright, © 2011-2022.  Edward Shore.   Unauthorized use and/or unauthorized distribution for commercial purposes without express and written permission from the author is strictly prohibited.  This blog entry may be distributed for noncommercial purposes, provided that full credit is given to the author. 

Casio fx-991EX Classwiz Tips: Solve for Any Variable

Casio fx-991EX Classwiz Tips:  Solve for Any Variable

This week I am going to show some things that can be done with the Casio fx-991EX Classwiz.  

Solving For Any Variable

The Casio Classwiz can solve equations in the main (Calculate) mode in the following formats:

Equation, i.e.  A + 2x = y^3

And Expression Equal to Zero, i.e. 2x^4 - 18  (the equal to zero is implied)

Pressing [SHIFT] [CALC] (SOLVE) allows us to enter values for all but one variable to solve for.   Enter values with the equals [ = ] key.  

When you select the variable to solve for, press the [ = ] key without entering a number.

Caution:  When you are entering equations, don't use the white [ = ] key.  To enter the = character, press [ALPHA] [ CALC ].

The L-R indicator tells the the accuracy of the solution.  We want L-R = 0.

Example:

2x^2 + 3y^3 = A

Keystrokes:  2 [ x ] [ x^2 ] [ + ] 3 [ALPHA] (Y) [SHIFT] (x^3) [ALPHA] (=) [ALPHA] (A)

[SHIFT] (SOLVE)

Inputs:  x = 8, y = 2, solve for A.   A = 152, L-R = 0

Inputs:  x = 6, A = 79, solve for y.  y = 1.326352406, L-R = 0

Inputs: y = 3.5, A = 105, solve for x.  Cannot Solve   (x has a complex number solution)

Eddie

All original content copyright, © 2011-2022.  Edward Shore.   Unauthorized use and/or unauthorized distribution for commercial purposes without express and written permission from the author is strictly prohibited.  This blog entry may be distributed for noncommercial purposes, provided that full credit is given to the author. 

Casio fx-991EX Classwiz Tips: Solving Inequalities

Casio fx-991EX Classwiz Tips:  Solving Inequalities

This week I am going to show some things that can be done with the Casio fx-991EX Classwiz.  

Solving Inequalities

Did you know that the Casio Classwiz can solve inequalities in the forms:

p(x) > 0

p(x) <0

p(x) ≥ 0

p(x) ≤ 0

where p(x) is a polynomial of degree 2 to 4.   The lead coefficient is nonzero.

To get there:  [MENU], [ ° ' " ] (B).

Each inequality and answers are displayed in textbook format.

Examples:

-4x^2 + 8x - 1 < 0

Result:  x < (2 - √3)/2, (2 + √3)/2 < x

-4x^2 + 8x - 1 > 0

Result:  (2 - √3)/2 < x < (2 + √3)/2

3x^4 + 0x^3 - 8x^2 - 6x + 5 ≥ 0

Result:  x≤0.5149391226, 1.8065398762≤x

Eddie

All original content copyright, © 2011-2022.  Edward Shore.   Unauthorized use and/or unauthorized distribution for commercial purposes without express and written permission from the author is strictly prohibited.  This blog entry may be distributed for noncommercial purposes, provided that full credit is given to the author. 

Casio fx-991EX Classwiz Tips: Solving a Linear System

Casio fx-991EX Classwiz Tips:  Solving a Linear System

This week I am going to show some things that can be done with the Casio fx-991EX Classwiz.  

Solving Linear Systems

The Classwiz can solve linear systems.  To enter the Equation mode:

[MENU], [(-)] for A, 1 for Simul Equation

Up to four variables can be solved for. 

One of the nice things of the Classwiz's Equation mode is that the equations as shown as it is written on paper.  

For a 3 x 3 system (with coefficients reset to 0):

0x  + 0y + 0z  = 0

0x  + 0y + 0z  = 0

0x  + 0y + 0z  = 0

with a large left bracket symbol, {, to the left of the equations.

Entering negative numbers will change the plus to minuses:  i.e.  5x - 6y instead of 5x + -6y.  

Use the equals key [ = ] to enter coefficients and call for solutions. 

Example:

- 2x + 11y + 3z = 25 

3x + 6y - 8z = 9

10x + 2y + 9z = -3

x = -1231/1479 ≈ -0.8323191346

y = 3086/1479 ≈ 2.086544963

z = 63/493 ≈ 0.1277890467

 

Eddie

All original content copyright, © 2011-2022.  Edward Shore.   Unauthorized use and/or unauthorized distribution for commercial purposes without express and written permission from the author is strictly prohibited.  This blog entry may be distributed for noncommercial purposes, provided that full credit is given to the author.