Chapter 4.2, Problem 18SB

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 $f\left(x\right)$.

18. $f\left(x\right)\text{ = }{x}^6\text{ - 16}{x}^4\text{ + }{x}^2$; $x\text{ + 4}$