Chapter 4.2, Problem 12SB

In Problems 11-20, use the Remainder Theorem to find the remainder when $f\left(x\right)$ is divided by $x\text{ - }c$. Then use the Factor Theorem to determine whether $x\text{ - }c$ is a factor of $f\left(x\right)$.

12. $f\left(x\right)\text{ = -4}{x}^3\text{ + 5}{x}^2\text{ + 8}$; $x\text{ + 3}$