Hey Tutu.

For 2) consider x = 2 instead of x = 1.

For 1) consider the binomial expansion (2 + 2)^n and how 4^n * [n]Cr gives [2n+1]Cr when you consider that adding all nCr's from 0 to n gives 2^n which means the square of this gives (2^n)^2 = 2^(2n) = (2^2)^n = 4^n.