Texas Instruments TI-92 Getting Started page 28

5.6.3 Row Operations: Here are the keystrokes necessary to perform elementary row operations on a matrix. Your
textbook provides a more careful explanation of the elementary row operations and their uses.
Figure 5.78: Swap rows 2 and 3
To interchange the second and third rows of the matrix a that was defined above, press 2nd MATH 4[Matrix]
D[Row ops] 1 [rowSwap(] A , 2 , 3 ) ENTER (see Figure 5.78). The format of this command is
rowSwap(matrix1, rlndex1, rIndex2).
To add row 2 and row 3 and store the results in row 3, press 2nd MATH 4[Matrix] D[Row ops] 2[rowAdd(] A, 2,
3) ENTER. The format of this command is rowAdd(matrix1, rlndex1, rIndex2).
To multiply row 2 by –4 and store the results in row 2, thereby replacing row 2 with new values, press 2nd MATH
4[Matrix] D[Row ops] 3[mRow(] (-) 4 , A , 2 ) ENTER. The format of this command is mRow(expression,
matrix1, index).
To multiply row 2 by –4 and add the results to row 3, thereby replacing row 3 with new values, press 2nd MATH
4[Matrix] D[Row ops] 4[mRowAdd(] (-) 4, A, 2, 3) ENTER (see Figure 5.79). The format of this command is m
RowAdd(expression, matrix1, Index1, Index2).
Note that your TI-92 does not store a matrix obtained as the result of any row operation. So, when you need to
perform several row operations in succession, it is a good idea to store the result of each one in a temporary place.
For example, use row operations to solve this system of linear equations:
First enter this augmented matrix as a in your TI-92:
this matrix as e (press A STO➧ E ENTER), so you may keep the original in case you need to recall it.
Here are the row operations and their associated keystrokes. At each step, the result is stored in e and replaces the
previous matrix e. The last two steps of the row operations are shown in Figure 5.80.
2 8
Graphing Technology Guide: TI-92
Copyright © Houghton Mifflin Company. All rights reserved.
Figure 5.79: Add –4 times row 2 to row 3
−

x

− +


−
2 x

−
 
1 2 3 9
 
− −
1 3 0 4 . Then return to the Home screen and store
 
 
−
2 5 5 17
 
+ =
2 y 3 z 9
= −
x 3 y 4 .
+ =
5 y 5 z 17