Casio fx-991AR X User Manual

Simultaneous linear equations
with two, three, or four
unknowns
Press (Simul Equation), and then
use a number key ( to ) to
specify the number of unknowns.
Quadratic equations, cubic
equations, or quartic equations
Press (Polynomial), and then use
a number key ( to ) to specify
the polynomial degree.
3. Use the Coefficient Editor that appears to input coefficient values.
• To solve 2x
2
+ x − 3 = 0, for example, press (Polynomial) in
step 2. Use the Coefficient Editor that appears to input
213.
• Pressing  will clear all of the coefficients to zero.
4. After all the values are the way you want, press .
• This will display a solution. Each press of  will display another
solution. Pressing  while the final solution is displayed will return to
the Coefficient Editor.
• A message appears to let you know when there is no solution or when
there are infinite solutions. Pressing  or  will return to the
Coefficient Editor.
• You can assign the currently displayed solution to a variable. While
the solution is displayed, press  and then the key that
corresponds to the name of the variable to which you want to assign
it.
• To return to the Coefficient Editor while any solution is displayed,
press .
Note: Solutions that include √ are displayed only when the selected
calculation type is Polynomial.
To change the current equation type setting: Press (Simul
Equation) or (Polynomial), and then press , , or . Changing
the equation type causes the values of all Coefficient Editor coefficients to
change to zero.
Equation/Func Mode Calculation Examples
x + 2y = 3, 2x + 3y = 4
(Simul Equation)
123234


(x=)
(y=)
-1
2
x
2
+ 2x − 2 = 0
(Polynomial)
122

(x
1
=)
(x
2
=)
-1 +
3
-1 −
3
(Displays x-coordinate of local minimum of y = x
2
+ 2x − 2.*)

(x=)
-1
(Displays y-coordinate of local minimum of y = x
2
+ 2x − 2.*)

(y=)
-3
* The x- and y-coordinates of the local minimum (or local maximum) of the
function y = ax
2
+ bx + c are also displayed, but only when a quadratic
equation is selected for the calculation type.
25

Casio fx-991AR X Specifications

General

Model	fx-991AR X
Category	Scientific Calculator
Type	Non-programmable
Number of Functions	552
Memory	9 variables
Manufacturer	Casio
Power Source	Solar and Battery

Summary

Using Menus

Calculation Mode

Selecting the appropriate mode for different types of calculations.

Inputting Expressions and Values

Calculation Priority Sequence

Order of operations for calculations on the calculator.

Inputting an Expression Using Natural Textbook Format

How to input formulas using natural textbook format.

Basic Calculations

Using Memory Functions

Variables (A, B, C, D, E, F, M, x, y)

Assigning values to variables for calculations.

Function Calculations

sin, cos, tan, sin⁻¹, cos⁻¹, tan⁻¹

Performing trigonometric and inverse trigonometric calculations.

log, ln

Performing logarithmic calculations with base 10 and base e.

Integration and Differential Calculation

Performing numerical integration and derivative calculations.

QR Code Function

Displaying a QR Code

Steps to display a QR code for a calculation result.

Complex Number Calculations

Complex Mode Calculation Examples

Examples of calculations involving complex numbers.

Using CALC

Using SOLVE

Statistical Calculations

Inputting Data with Statistics Editor

Entering data for statistical analysis using the editor.

Displaying Statistical Values Based On Input Data

Recalling statistical values like mean, variance.

Displaying Regression Calculation Results Based On Input Data

Displaying regression coefficients and formulas.

Obtaining Statistical Values from Input Data

Recalling statistical variables and using them in calculations.

Performing Normal Distribution Calculations

Base-n Calculations

Logical and Negation Operations

Performing bitwise logical and negation operations.

Equation Calculations

Equation/Func Mode Calculation Examples

Matrix Calculations

Assigning and Editing Matrix Variable Data

Creating a Number Table

Vector Calculations

Assigning and Editing Vector Variable Data

Vector Calculation Examples

Inequality Calculations

Inequality Mode Calculation Examples

Ratio Calculations

Using Spreadsheet

Inputting and Editing Cell Contents

Entering constants and formulas into spreadsheet cells.

Cell Relative and Absolute References

Batch Inputting the Same Formula or Constant into Multiple Cells

Metric Conversion

Errors

Error Messages

Explains common error messages and their causes.

Replacing the Battery