Exercise 57 Page 491

We want to identify the initial amount a and the growth factor b in the given exponential function. To do so, let's first recall the general form of an exponential growth function. y= a * b^x, where a>0 and b>1 Here, a is the initial amount and the base b is the growth factor, which equals 1 plus the percent rate of change expressed as a decimal. Let's now consider the given function. y= 3 * 4^x We see that a= 3 and b= 4. Therefore, the growth factor is 4.