Functions take us places: you put in a number, and another number results. For linear functions, we move at a constant rate of change, which is the slope of the line. Other functions exhibit different types of behavior, and if we are given the input number, we can determine the result.

But what happens when we know the result, and need to find that number which produced it? This is the area of inverse functions. If you are given the result of a function, or its y value, how do you determine the initiating x value? You have previously studied the opposite, or inverse of functions.

In the next topic of this module, we will examine the inverse of the exponential function, which is called the logarithm.