TITLE: Purpose of Inverse Functions
QUESTION [21 upvotes]: Finding inverse functions and understanding their properties is fairly basic within mathematics. During my studies it was found fairly simple and easy to comprehend that it was a swapping of the outputs and inputs of a function. But now it has reappeared in calculus as finding the derivative of inverse functions and has me thinking  what is the actual real world application of inverses.Like how studying quadratics is extremely useful in modeling objects in free fall. I know my question may seem trivial to many here, i'm a high school student and we never get to have these discussions in class.

REPLY [2 votes]: Another more complex set of examples comes from the area of study usually called the Time Value of Money. This problem domain is full of functions and inverses that allow you to compute missing terms of a loan from various viewpoints. For example, given a sum to borrow, say, $1 million, an interest rate, say, 10%, and a number of periods (months or years), how much must I pay each period to retire (pay off) the loan. Conversely, if you want to pay $25,000 per period, how many payments must you make to retire the debt?