## Precalculus: Concepts Through Functions, A Unit Circle Approach to Trigonometry (3rd Edition)

Remainder = $0$ $(x+4)$ is a factor of $f(x)$.
The Remainder Theorem states that when a function $f(x)$ is divided by $(x-R)$ , then the remainder will be: $f(R)$. We have: $f(x)=x^6-16x^4+x^2-16$ $\implies f(-4)=(-4)^6-16(-4)^4+(-4)^2-16= 4096-4096=0$ The Factor Theorem states that if $f(a)=0$, then $(x-a)$ is a factor of $f(x)$ and vice versa. Therefore, by the Factor Theorem $(x+4)$ is a factor of $f(x)$.