This post about how you evaluate a function is part of a series of posts to help you prepare for the Advanced Algebra and Functions part of the Accuplacer test.
To evaluate a function means to find the function’s y-value if you are given an x-value.
Let’s say you’re given this function:
and you’re asked to find f(10) — in other words, the value of f where x=10.
To do that, substitute 10 into the equation for f where you see x:
Now clean it up: Substitute 8 for 10-2:
And multiply 4 by 8:
And that’s all there is to evaluating this function.
The example in this post is a linear function.
See How Do You Evaluate a Function? II for an example of how to evaluate a quadratic function.
This question is similar to question number 1 in the sample questions for the Accuplacer Advanced Algebra and Functions test.