Due: 05 October 2011
Math 1090-002
28 September 2011
Section 2.4 Homework
Instructions: Complete the following problems in the space provided. Do all
parts. Please show your work; write down enough so that a classmate could
follow the steps you’ve taken to arrive at the solution. (Note: Only the starred
problems come from the text.)
For each of the square matrices given below, do the following:
> Find the inverse of each matrix, or state that no inverse exists.
> In the cases that you are able to compute an inverse, check your work. (For
example, given a matrix M, if M −1 exists, compute both M M −1 and
M −1 M . In both cases your should get I.
1. (4 points)
"
A=
4
7
3
5
1
#
2. (4 points)
"
B=
−1
−2
3
6
2
#
3. (5 points)

−2
2

C =  −1
2
1
3
1


3 
0 −1
Solve each system of linear equations using an inverse matrix.
27*. (4 points)
−x + 2y = 30
8x − y = 60
4
29*. (4 points)
x+y+z =2
x − y + z = −2
x−y−z =0
5
6. (4 points)
−2x + y + 3z = 4
x−y =1
−x + 3z = −5
6