The continuous uniform random variable $X$ has density function
$$
F(x)=\frac{1}{\beta-\alpha}, \quad \alpha \leq x \leq \beta
$$
(a) Show that the moment-generating function is
$$
M_{X}(t)=\frac{e^{t \beta}-e^{t \alpha}}{t(\beta-\alpha)}
$$
(b) Use $M_{X}(t)$ to find the mean and variance of $X$.