### Home > INT3 > Chapter 5 > Lesson 5.2.3 > Problem5-84

5-84.

Given $f(x) = -2x^2 - 4$ and $g(x) = 5x + 3$:

1. What is $f(–7)$?

$f(-7)=-2(-7)^2-4$

1. What is $g(–2)$?

Refer to the step in part (a).

1. If $f(x) = c$, what is $x$?

First, set the function equal to $c$. Then solve for $x$.

$x\ =\ \sqrt{\frac{c+4}{-2}}$

1. If $g(x) = c$, what is $x$?

Refer to part (c). Follow the same process.

1. Write an equation for $g^{–1}(x)$.

How can you undo multiplying by $5$ and adding $3$?