### Section 4.0 - Why Bother?

Up to now, you may have only
considered
power expressions in which the exponents are constants, but in this
module we study functions defined by equations
involving variables in the exponents. Such functions are called *exponential functions* (or *logarithmic
functions* if it is the
dependent variable in the exponent).

The reason we study such
functions is
because they occur in many important applications. Population
growth, compound interest, radioactivity,
electric
circuits, and heat flow are just a few. After considering some of these
you
should be able to recognize and explain the occurrence of exponential
functions
in other areas as well.

#### What to do

After reading about the linked
examples
above, try to express in your own words why the others might also give
rise to
the occurrence of exponential functions. Check that you have met the Learning Objectives for this section before
proceeding to the next section.

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4.5 Lab