Answer
$3,-2$
Work Step by Step
Possible rational zeros are $\pm1,\pm2,\pm4$
a. for upper bound, use synthetic division, test values $4,3,2,..$, we found $3$ is an upper bound (2 is not)
as shown in the synthetic division, all the numbers of the quotient and remainder line are positive (zeros as positive).
b. for lower bound, test values $-4,-3,-2...$ and we found $-2$ is a lower bound as shown in the synthetic division, the numbers of the quotient and remainder line have alternating signs.
(Actually, $-1$ is both a zero and a lower bound.)
