Exercise 98 Page 471

a Since the balance increases by a percentage, we can model it with an exponential function.

y = a b^{x}

b When Kristin has her

1 6^{th}

birthday, sixteen years will have passed since the account started. Therefore, if we substitute

x = 16

into the formula we can calculate the amount of money the account has at this time.

c The domain tells us which values of

x

the function is defined for, and the range is the values that the function can take on

y

given the domain. Since the account was started when

x = 0,

the function's domain is limited to non-negative numbers of

x .

d To graph the situation we will first find the amount of money in the account during a few of Kristin's birthdays.

8.2.1 Curve Fitting p.471-472

8.2.2 Curved Best-Fit Models p.478-480

8.2.3 Solving a System of Exponential Functions Graphically p.483-484