Answer:
Step-by-step explanation:
Given that A is a square matrix and A is idempotent

Consider I-A
i) 
It follows that I-A is also idempotent
ii) Consider the matrix 2A-I

So it follows that 2A-I matrix is its own inverse.
-12
lmk if you want me to explain
Answer:
x=6.67
Step-by-step explanation:
knowns:
both angles are equal to each other
so:
7x-15=4x+5
3x=20
x=20/3
x=6.666
Answer: No, he needed to apply the exponent to all factors in the product in the second step.