 is the growth factor in an exponential function. The function decays, stays constant, or grows as 

What Is the Role of the Base b in an Exponential Function?

A growth factor helps you calculate a final amount after a percentage has been added or subtracted. It is given by the formula:

 is the decimal representation of the percentage that is being added or subtracted.

A decay factor helps you calculate a final amount after a percentage has been subtracted. It is given by the formula:

 is the decimal representation of the percentage that is being subtracted.

The part of a power showing the factor that is multiplied by itself.

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Definition

The base b is the growth factor in an exponential function. The function decays, stays constant, or grows as x increases. This video explains more.