Question

Confused on how to do this

Answer 1

$(fg)(x)$ is shorthand for $(f\times g)(x)=f(x)\times g(x)$.

So if $f(x)=x^2-4$ and $g(x)=3x+5$, then

$(fg)(x)=f(x)\times g(x)=(x^2-4)(3x+5)=\cdots$

Finding the value of $(fg)(-1)$ is just a matter of replacing $x$ with -1. We get

$(fg)(-1)=f(-1)\times g(-1)=((-1)^2-4)(3(-1)+5)=(1-4)(-3+5)=(-3)(-2)=6$