Question

Need an explanation... (Matrices)

Answer 1

Why is the answer (a)?

Answer 2

\[A=A ^{-1}~operate~both~sides~by~A\]
\[AA=AA ^{-1}=I,~Or~A ^{2}=I,\left( A^2 \right)^n=I^n=I,A ^{2n}=I\]

Answer 3

Alright, got it! Thanks a lot!

Answer 4

yw