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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