# How Do You Evaluate a Function? I

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.

## Question

Let’s say you’re given this function:

$\fn_jvn {\color{Blue} f(x)=4\left ( x-2 \right )}$

and you’re asked to find f(10) — in other words, the value of f where x=10.

## Solution

To do that, substitute 10 into the equation for f where you see x:

$\fn_jvn {\color{Blue} f(10)=4\left ( 10-2 \right )}$

Now clean it up: Substitute 8 for 10-2:

$\fn_jvn {\color{Blue} f(10)=4 \cdot 8}$

And multiply 4 by 8:

$\fn_jvn&space;{\color{Blue}&space;f(10)=32}$

So f(10)=32..

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.

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