### Home > PC > Chapter 9 > Lesson 9.1.3 > Problem9-45

9-45.

Given $f(x)=10x^2$ and $g(x)=15-3x$, find the following

1. $f(3+h)-90$

Substitute $(3+h)$ for every '$x$' in the '$f$' function, then subtract $90$. Simplify.

1. $f(x+h)-10x^2$

$10(x+h)^2-10x^2$

1. $g(20+h)$

Substitute $(20+h)$ for every '$x$' in the '$g$' function. Simplify.

1. $f(g(x))$

Substitute $(15-3x)$ for every '$x$' in the '$f$' function. Simplify.

$10(15-3x)^2$