How to determine $E[X^3]$ given $E[X^2]$ and $E[X]$

Question

Let $X$ be a discrete random variable with $E[X] = 2$ and $E[X^2] = 4$. Find $E[(2 + X)^3]$.

When I proceed to $E[2+4X+8X^2+X^3]$

I don't know how to calculate $E[X^3]$.

Answer 1

Since the variance of $X$ is zero, $X$ is almost surely constant (and therefore is constant, since it's discrete). The value of $X$ must be $2$, so the answer is $64$.