Sharp EL9900 manual 2Calculate B-1C

EL-9900 Graphing Calculator

Step & Key Operation

2-1Enter a 3 x 3 matrix B.

2nd F MATRIX B 2 3 ENTER 3 ENTER

1 ENTER 2 ENTER 1 ENTER

2 ENTER 1 ENTER (-) 1 ENTER

1 ENTER 1 ENTER (-) 2 ENTER

2-2Exit the matrix editor and find the inverse of the square matrix B.

2nd F	QUIT	CL
			2
2nd F	MATRIX	A		2nd F	x-1	ENTER

(repeatedly)

3-1Enter the constants on the right side of the equal sign into matrix C (3 x 1).

2nd F MATRIX B 3 3 ENTER 1 ENTER

8 ENTER 1 ENTER (-) 3 ENTER

3-2Calculate B-1C.

CL 2nd F MATRIX A 2

2nd F x-1 X 2nd F MATRIX A 3 ENTER

3-3Delete the input matrices for future use.

2nd F OPTION C

2 ENTER

2nd F QUIT

DisplayNotes

Some square matrices have no inverse and will generate error statements when calcu- lating the inverse.

B-1=		- 0.17	0.83	- 0.5
	0.5 - 0.5			0.5
		0.17	0.17	- 0.5

The system of equations can be expressed as

	1	2	1	x	=		8
2		1	-1	y		1
1		1	-2	z		-3

Let each matrix B, X, C : BX = C

B-1BX = B-1C (multiply both sides by B-1)

I= B-1(B-1B = I, identity matrix) X = B-1C

The 1 is the x coordinate, the 2 the y coordinate, and the 3 the z coordinate of the solution point.

(x, y, z)=(1, 2, 3)

The calculator can execute calculation of inverse matrix and matrix multiplication. A system of linear equations can be solved easily using the Matrix feature.

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