### Home > CC4 > Chapter 8 > Lesson 8.2.1 > Problem8-96

8-96.
1. Write a possible exponential function in y = a · bx form that represents each situation described below. Homework Help ✎

1. Has a y‑intercept of (0, 2) and passes through the point (3, 128).

2. Passes through the points (0, 4) and (2, 1).

Since it has an initial value of 2, the value of a is 2.
Substitute this into the general equation: y = abx.

Substitute the values 3 for x and 128 for y, then solve for b.

Create two equations substituting the values of the ordered pairs for x and y into the equation y = abx.

Solve the system of equations for a and b.

Be sure you use your results for a and b to write the equation.

$y = 4 \cdot \left(\frac{1}{2}\right)^{x}$