II $P(x)=(x-a)^{2} Q(x),$ where $Q(x)$ is a polynomial and $Q(a) \neq 0,$ we call $x=a$ a double zero of the polynomial $P(x)$
(a) If $x=a$ is a double zero of a polynomial $P(x)$ show that $P(a)=P^{\prime}(a)=0$
(b) If $P(x)$ is a polynomial and $P(a)=P^{\prime}(a)=0$ show that $x=a$ is a double zero of $P(x)$