Week 5 0B2 Review Sessions

Which of the following sums are possible?

• A+C

• A+B

• C+A

• B+A

Which of the following scalar products are possible?

• 0C

• 5A

• 5B

• 5C

Which of the following matrix products are possible?

• AC

• AB

• BA

• BC

• None of these.

If we have two matrices A and B that can be added, is it necessarily true that A+B=B+A?

• Yes

• No

If we have two matrices A and B that can be multiplied both AB and BA can be formed, is it necessarily true that AB=BA?

• Yes

• No

What is the (1,2)-th entry of the product AB.

• 0

• 4

• 1

• -1

• 10

What is (2,1)-th entry of the inverse of the matrix in the picture?

• -1/9

• -3/5

• -2/3

• -1/10

• 0