im stuck on these questions.....

1. If X is a standard normal random variable, find
a) the p.d.f of X^3
b) the p.d.f of (X+1)^2

and......

2. If Z has a standard normal distribution then using m.g.fs show that the random variable X=2Z + 4 also has a normal distribution, and write down its mean and variance

plz help