No idea how to do part (a). Can someone please help me? Thanks!
I think we will have to assume that the possible values of $\displaystyle x$ are integers, then:
(a) well obviously we have:
$\displaystyle p_X(x)=0,\ x<-1$
and
$\displaystyle p_X(x)=0,\ x \ge 1$,
so that leaves only $\displaystyle p_X(-1)$ and $\displaystyle p_X(0)$ to be determined, can you do that?
RonL