A random variable XXX has PDF f(x)=4x3f(x) = 4x^3f(x)=4x3 on [0,1][0, 1][0,1]. Find E[Xk]E[X^k]E[Xk].
4k+4\frac{4}{k+4}k+44
k+14\frac{k+1}{4}4k+1
1k+1\frac{1}{k+1}k+11
4k+1\frac{4}{k+1}k+14