Answer:
second one
Step-by-step explanation:
Let

be the identity matrix. Then pick whatever matrix you like for

.
Answer:
The answer to your question is 
Step-by-step explanation:
Here, there is a difference of squares, so just solve it and simplify

Multiply the binomials
= 1 - 
Simplify
= 
= 
Answer: D
Step-by-step explanation: