CPM Homework Help : CCA2 Problem 2-72

CPM Homework Banner

Home > CCA2 > Chapter 2 > Lesson 2.1.5 > Problem 2-72

2-72.

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

$(2,9)$ and $(4,324)$
Hint 1(a):
Use the equation $y=ab^x$ to help you here. Begin by substituting one of the points for $x$ and $y$ .
Hint 2(a):
Next, substitute the other ordered pair for $x$ and $y$ .
$9=ab^{2}$
$a=\frac{9}{b^{2}}$
More Help 1(a):
Use substitution, and solve for $b$ .
$324=ab^{4}$
$a=\frac{324}{b^{4}}$
More Help 2(a):
Now, solve for $a$ .
$\frac{9}{b^{2}}=\frac{324}{b^{4}}$
$9b^{4}=324b^{2}$
$9b^{2}=324$
$b^{2}=36$
$b=6$
Answer (a):
$y = 0.25\cdot 6^{x}$

$(−1,40)$ and $(0,12)$
Hint (b):
Look at the hints in part (a).
Answer (b):
$y=12\cdot0.3^x$

Use the eTool below to help you solve part (a).
Click the link at right for the full version of the eTool: CCA2 2-72a HW eTool

Use the eTool below to help you solve part (b).
Click the link at right for the full version of the eTool: CCA2 2-72b HW eTool

© 2022 CPM Educational Program. All rights reserved.