# CASIO

User´s Guide

## Using SOLVE

SOLVE uses Newton's method to approximate the solution of equations.
Note that SOLVE can be used in the COMP Mode only.
The following describes the types of equations whose solutions can be obtained using SOLVE.

Equations that include variable X: X2 + 2X - 2, Y = X + 5, X = sin(M), X + 3 = B + C
SOLVE solves for X. An expression like X2 + 2X - 2 is treated as X2 + 2X - 2 = 0.

Equations input using the following syntax: {equation}, {solution variable}
SOLVE solves for Y, for example, when an equation is input as: Y = X + 5, Y

### Important!

If an equation contains input functions that include an open parenthesis (such as sin and log), do not omit the closing parenthesis.

The following functions are not allowed inside of an equation: , d/dx, Σ, Π, Pol, Rec, ÷R.

Example: To solve y = ax2 + b for x when y = 0, a = 1, and b = -2

• (Y)(=)
(A)(X)(B)
• (SOLVE)
• (1) Prompts for input of a value for Y

(2) Current value of Y

• 012
• (3) Current value of X

Input an initial value for X (Here, input 1):

• 1
• Solution Screen

• To exit SOLVE:

### Note

During the time from when you press (SOLVE) until you exit SOLVE by pressing , you should use Linear Display input procedures for input.

### Important!

Depending on what you input for the initial value for X (solution variable), SOLVE may not be able to obtain solutions. If this happens, try changing the initial value so they are closer to the solution.

SOLVE may not be able to determine the correct solution, even when one exists.

SOLVE uses Newton's method, so even if there are multiple solutions, only one of them will be returned.

Due to limitations in Newton's method, solutions tend to be difficult to obtain for equations like the following: y = sin(x), y = ex, y = √x.

### Solution Screen Contents

Solutions are always displayed in decimal form.

(1) Equation (The equation you input.)
(2) Variable solved for
(3) Solution
(4) (Left Side) - (Right Side) result

"(Left Side) - (Right Side) result" shows the result when the right side of the equation is subtracted from the left side, after assigning the obtained value to the variable being solved for. The closer this result is to zero, the higher the accuracy of the solution.

### Continue Screen

SOLVE performs convergence a preset number of times. If it cannot find a solution, it displays a confirmation screen that shows "Continue: [=]", asking if you want to continue.

Press to continue or to cancel the SOLVE operation.

Example: To solve y = x2 - x + 1 for x when y = 3, 7, and 13.

• (Y)(=)
(X)(X)1
• (SOLVE)
• 3

Input an initial value for X (Here, input 1):

• 1
• 7
• 13