Mathematics » Introducing Integers » Multiply and Divide Integers

# Evaluating Variable Expressions with Integers

## Evaluating Variable Expressions with Integers

Now we can evaluate expressions that include multiplication and division with integers. Remember that to evaluate an expression, substitute the numbers in place of the variables, and then simplify.

## Example

$$\text{Evaluate}\phantom{\rule{0.2em}{0ex}}2{x}^{2}-3x+8\phantom{\rule{0.2em}{0ex}}\text{when}\phantom{\rule{0.2em}{0ex}}x=-4.$$

### Solution

 Simplify exponents. Multiply. Subtract. Add.

Keep in mind that when we substitute $$-4$$ for $$x,$$ we use parentheses to show the multiplication. Without parentheses, it would look like $$2·{-4}^{2}-3·-4+8.$$

## Example

$$\text{Evaluate}\phantom{\rule{0.2em}{0ex}}3x+4y-6\phantom{\rule{0.2em}{0ex}}\text{when}\phantom{\rule{0.2em}{0ex}}x=-1\phantom{\rule{0.2em}{0ex}}\text{and}\phantom{\rule{0.2em}{0ex}}y=2.$$

### Solution

 Substitute $$x=-1$$ and $$y=2$$. Multiply. Simplify.

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