**Casio Graphing Calculators: Equation Variables **

**Introduction**

Most modern Casio graphing calculators have an Equation solver mode that solves linear systems (Simultaneous), polynomials (Polynomial), and general equations.

To find run Equation mode, press [ MENU ] { A }*.

(*Equation mode is currently option A (fx-9750GIII, fx-CG 50, fx-CG 10/20, fx-9860 Slim))

**Simultaneous
Equations: SimRes and SimCoef**

The simultaneous equation mode solves linear systems up to 6 x 6. The coefficients of the equations are stored in the variable Sim Coef (labeled SimCoef in VARS-EQUATION menu) while the results are stored in the variable Sim Result (labeled SimRes).

**Polynomials:
PlyRes and PlyCoef**

The polynomial equation mode solves polynomials with real coefficients up to degree 6 (3 in early graphing models). The coefficients of the polynomial are stored in the variable Poly Coef (labeled PolyCoef in the VARS-EQUATION menu) while the results are stored in the variable Poly Result (labeled PolyRes).

**Accessing
Equation Variables Outside of Equation Mode**

The four equation variables can be recalled by pressing [ VARS ], [ F6 ] { > }, [ EQUA ] { F3 }.

F1: SimRes (S·Rlt on older models)

F2: SimCoef (S·Cof on older models)

F3: PlyRes (P·Rlt on older models)

F4: PlyCof (P·Cof on older models)

The four variables are read-only matrices. We can not store values or information to read-only variables.

If we want
to extract specific values from the equations variables, we must
store them into a Matrix variable (A – Z, θ). For example, to
retrieve the number from the 1^{st} row and column of Sim
Coef:

Sim Coef → Mat A

Mat A[1,1]

We can execute operations on equation variables. An interesting check is to run the simultaneous solver of the variable by typing:

Rref Sim Coef

and reading the last column.

Until next time,

Eddie

All original content copyright, © 2011-2024. 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.