Chapter 3 - Section 3.4 - Real Zeros of Polynomials - 3.4 Exercises - Page 284: 78

$-2,+3$

The possible rational zeros are $\pm1,\pm\frac{1}{2},\pm2,\pm3,\pm3/2,\pm4,\pm6,\pm12$ a. Test upper bounds with integers $12,11,10,...$, we can found that $+3$ is an upper bound as shown in the synthetic division, while $+2$ is not. b. Test lower bounds with integers $-12,-11,-10,...$, we found a lower bound at $-2$