# How do you evaluate variable expressions?

##### 1 Answer

To evaluate a variable expression means to find the value of the expression when the variable is (or variables are) replaced by a number (or numbers).

Here is a variable expression:

To evaluate this **expression when #x = 2#** mean to substitute

When

If we evaluate the same expression when

**Here's a variable expression with two variables** :

In order to evaluate this expression, we'll need values (numbers) for both

Evaluate the expression

If we change the values to

**Note:**

To avoid saying exactly the same thing over and over, we use the following to mean the same thing:

evaluate the expression when

evaluate the expression for

evaluate the expression at

evaluate the expression assuming

evaluate the expression if

**Also**

If there is only one variable in an expression, we don't always need to mention it:

evaluate the expression for

evaluate the expression at