Wednesday, September 7, 2022

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


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