Evaluating Variable Expressions with Integers
Evaluating Variable Expressions with Integers
Remember that to evaluate an expression means to substitute a number for the variable in the expression. Now we can use negative numbers as well as positive numbers when evaluating expressions.
Example
Evaluate \(x+7\phantom{\rule{0.2em}{0ex}}\text{when}\phantom{\rule{0.2em}{0ex}}\)
- \(\phantom{\rule{0.2em}{0ex}}x=-2\phantom{\rule{0.2em}{0ex}}\)
- \(\phantom{\rule{0.2em}{0ex}}\phantom{\rule{0.2em}{0ex}}x=-11.\)
Solution
| Evaluate \(x+7\) when \(x=-2\) | |
| Simplify. |
| Evaluate \(x+7\) when \(x=-11\) | |
| Simplify. |
Example
When \(n=-5,\) evaluate \(\)
- \(\phantom{\rule{0.2em}{0ex}}n+1\phantom{\rule{0.2em}{0ex}}\)
- \(\phantom{\rule{0.2em}{0ex}}-n+1.\)
Solution
| Evaluate \(n+1\) when \(n=-5\) | |
| Simplify. |
| Evaluate \(-n+1\) when \(n=-5\) | |
| Simplify. | |
| Add. |
Example
Evaluate \(3a+b\) when \(a=12\) and \(b=-30.\)
Solution
| Multiply. | |
| Add. |
Example
Evaluate \({\left(x+y\right)}^{2}\) when \(x=-18\) and \(y=24.\)
Solution
This expression has two variables. Substitute \(-18\) for \(x\) and \(24\) for \(y.\)
| \({\left(x+y\right)}^{2}\) | |
| \({\left(-18+24\right)}^{2}\) | |
| Add inside the parentheses. | \({\left(6\right)}^{2}\) |
| Simplify | \(36\) |
Optional Video: Example on Adding Integers by Mathispower4u
This lesson is part of:
Introducing Integers
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