Texas Instruments PLUS TI-89 - Manual (Page 405)

388 Chapter 23: Activities
23ACTS.DOC TI-89/TI-92 Plus: Activities (English) Susan Gullord Revised: 02/23/01 1:24 PM Printed: 02/23/01 2:20 PM Page 388 of 26
Perform these steps to generate a random matrix, augment and find
the identity matrix, and then solve to find an invalid value of the
inverse.
1. On the Home screen, use
RandSeed to set the random
number generator seed to the
factory default, and then use
randMat() to create a random
3x3 matrix and store it in a .
2. Replace the [2,3] element of the
matrix with the variable x , and
then use the augment()
function, to augment the 3x3
identity to
a and store the
result in b .
3. Use rref() to “row reduce”
matrix b :
The result will have the
identity matrix in the first
three columns and
a^ ë 1 in the
last three columns.
4. Solve for the value of x that
will cause the inverse of the
matrix to be invalid.
Enter: solve(getDenom(
2 ± [1,4] )=0,x)
Result: x= ë 70/17
Exploring a Matrix
This activity shows you how to perform several matrix
operations.
Exploring a 3x3
Matrix
Tip: Use the cursor in the
history area to scroll the
result.
Tip: Use the cursor in the
history area to scroll the
result.