Evaluating Functions



function machine in algebra

In our introduction to functions lesson, we related functions to a vending machine. You "input" money and your "output" is candy or chips! We're going to go back to that visual as we evaluate functions. We are going to "input" a number and our "output is the answer!





Let's take a look at a few examples!


Example 1

evaluating functions

Did you notice how we just substituted for x and we found our answer? Not too hard, is it?

Next you will see how using function notation makes it easier to display your answer if you are asked to evaluate the function more than one time!



Example 2

evaluating functions in algebra

Do you see how easy it is to keep our answer organized since we have two answers to display? We label them as f(-2) and f(3) to keep them organized!


I hope you are finding this to be pretty easy! You actually already know how to evaluate functions if you can evaluate equations. We are just giving it a different name!

Are ready for a few practice problems?





evaluating functions practice problems

Practice Problems


1. Given the function: h(x) = -3x -5, find h(4) & h(-3).


2. Given the function: f(x) = x2+ 3x - 4, find f(-1) & f(4)











Answer Key


Problem 1

evaluating functions practice problems



Problem 2

evaluating functions solutions

Great Job! I hope that you found evaluating functions pretty easy after all!




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