Answer
$-1, 1, -2, 2, -4, 4, -8, \text{ and } 8$
Work Step by Step
Note that:
$-8 = 4(-2)
\\-8 =-4(2)
\\-8=8(-1)
\\-8=-8(1)$
So the factors of $-8$ are $\pm1, \pm2, \pm4, \pm8$.
while
$\\2=2(1)
\\2=(-2)(-1)$
So the factors of $2$ are $\pm1, \pm2$
Thus,
The possible values of $p$ are $\pm1, \pm2, \pm4, \pm8$.
The possible values of $q$ are $\pm1, \pm2$
Therefore the possible rational zeros $\frac{p}{q}$ of $R(x)$ are:
$\\-1, 1, -2, 2, -4, 4, -8, \text{ and } 8$