Exercise 46 Page 287

Let's start by recalling the general formula of exponential growth and exponential decay functions. cc Exponential Growth & Exponential Decay [0.8em] y=a(1+r)^t & y=a(1-r)^tIn both cases a and r are positive numbers. For exponential decay, r is less than 1. Let's rewrite the given function to match one of the above formulas.

Our function matches the format of exponential decay. Here a= 1 and r= 0.2. y= 1(1- 0.2)^t This means that the rate of decay, also known as the percent of change, is 20 %.