### Home > CCA2 > Chapter 5 > Lesson 5.2.1 > Problem5-61

5-61.

Consider the function of $f(x)=\frac{2}{7-x}$.

1. What is $f(7)$?

Substitute $7\ \text{for}\ x$.

2. What is the domain of $f(x)$?

Division by $0$ is undefined. What x-value causes division by $0$ for this function?
$x$ cannot have that value.

3. If $g(x)=2x+5$, what is $g(3)$?

Substitute $3\ \text{for}\ x$.

4. Now use the output of $g(3)$ as the input for $f$ to calculate $f(g(3))$.

$g(3)=11$, therefore calculate $f(11)$.