Math

1

Spring 2020 Name: _________________________ MATH 175 – Test 2 - Part 2 (Show Your Work )

6. Let 1 5 4

0 3 6 A

−  =    

and 6 12 0

3 9 6 B

−  =    

. Find 2

2 3

A B− + .

7. Let 4 2

5 3 A

−  =  

−  and

5 4

6 2

0 7

B

   

= −     

. Find BA .

8. Let

5 4

6 2

0 7

B

   

= −     

and 5 4 2

3 0 7 C

−  =  

−  . Find BC .

2

9. Solve 3 12

2 11

x y

x y

+ = − 

− = by using the inverse of the coefficient matrix

10. Solve

5 18

3 3 6

3 2 13

x y z

x y z

x y z

+ − = − 

− + =  + − = −

by using the inverse of the coefficient matrix

Hint: [ 1 1 − 5 3 −3 1 1 3 −2

]

−1

= 1

50 [

−3 13 14 −7 −3 16

−12 2 6 ]