Can someone please help me with these math questions?

I really need some help because these are some of the exercises that will be on the final test...i think i found the solution to some of these but i am not sure....i would really appreciate your help.

1)find a and b if 4x^4 + ax^3 + bx^2 + 6x + 1 = [P(x)]^2

2)Find P(5) - P(3) if P(2x) + P(4x) + P(6x) = 24x - 6

3)Find the polynomials which satisfy 2P(x) = P(2x)

4)Find P(x) if P(x - 2 ) + P(x + 1) = 6x + 5

and the last

5) Find Q(x) if Q(x) x Q(2x)= 8x^2 + 30x + 25

Thank you very much