## Definition Of Exponential Function

An Exponential Function is a function of the form y = abx, where both a and b are greater than 0 and b is not equal to 1.

Exponential Decay
Exponential decay occurs when a quantity decreases by the same proportion r in each time period t. If A0 is the initial amount, then the amount at time t is given by A = A0(1 - r)t, where r is called the decay rate, 0 < r="">< 1,and="" (1-r)="" is="" called="" the="" decay="">
Exponential Growth
Exponential growth occurs when a quantity increases by the same proportion r in each time period t. If A0 is the initial amount then the amount at time t is given by A = A0(1 - r)t, where r is called the growth rate, 0 < r="">< 1,="" and="" (1="" +="" r)="" is="" called="" the="" growth="" factor.="">

### Example of Exponential Function

y = 4.3(1.23)X is an exponential function.

A. 160
B. 625
C. 140
D. 80.58