### Home > CCA > Chapter 7 > Lesson 7.2.2 > Problem7-99

7-99.
1. If f(x) = 3(2)x, find the value of the expressions in parts (a) through (c) below. Then complete parts (d) through (f). 7-99 HW eTool (Desmos). Homework Help ✎

1. f(−1)

2. f(0)

3. f(1)

4. What value of x gives f(x) = 12?

5. Where does the graph of this function cross the x-axis? The y-axis?

6. If g(x) = , find f(x) · g(x).

Substitute −1 for x and simplify.

f(−1) = 3(2)−1

$=3\cdot\frac{1}{2}$

$\frac{3}{2}$

Refer to part (a).

Refer to part (a).

Substitute 12 for f(x) and solve for x.

x = 2

A function crosses the x-axis at y = 0, and a function crosses the y-axis at x = 0.

$\text{Substitute }3(2)^{x}\text{ for }f(x)\text{ and }\frac{1}{3x}\text{ for }g(x).$

Use the eTool below to find the value of each expression in parts (a) through (c).
Click on the link at right for the full eTool version: CCA 7-99 HW eTool