hi, some more matrices problems that i can't solve

no 1 :

a) Find PQ which i did =

i can't solve b which is

b) Find a matrix X such that PX + Q = P

no2) If work out and

hence show that

i worked out x^2 and X^3 , and i tried doing the above calculations but didn't get x^3

what should i do?

thanks in advance