### Home > INT3 > Chapter 4 > Lesson 4.4.2 > Problem4-118

4-118.

Write the equation of an exponential function that passes through each pair of points.

1. $(2,9)$ and $(4,324)$

Substitute the points into the equation $y=ab^x$.
$9 = a \cdot b^2$
$324 = a \cdot b^4$

Solve one equation for a and substitute to solve for $b$.

$a = \frac{9}{b^2}$

Use the value of $b$ to solve for $a$.
$324 = \bigg(\frac{9}{b^2}\bigg) \cdot b^4$

$y = 0.25 \cdot 6^x$

1. $(-1,40)$ and $(0,12)$

Follow the same process as the steps given in part (a).