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# Evaluating expressions review

An algebraic expression like 3x can be evaluated for any value of x. Say x=4, then 3x = 3*4 = 12. In this article, we review how to evaluate algebraic expressions.

## What does it mean to evaluate an algebraic expression?

An algebraic expression like 2, x, plus, 3 can be evaluated by substituting a value for x. For example, if x, equals, start color #11accd, 4, end color #11accd then:
\begin{aligned} &2x+3 \\\\ =& 2\cdot \blueD{4}+3 \\\\ =& 8+3 \\\\ =& 11 \end{aligned}
We can also evaluate more complicated expressions that have more than one variable. For example, we can evaluate 10, plus, 2, p, minus, 3, r when p, equals, start color #11accd, 4, end color #11accd and r, equals, start color #e07d10, 5, end color #e07d10:
\begin{aligned} &10 + 2p - 3r \\\\ =& 10 + 2\cdot\blueD 4 - 3 \cdot \goldD5 \\\\ =& 10 + 8 - 15 \\\\ =& 3 \end{aligned}
Want to learn more about evaluating expressions? Check out this video. And here's a word problem video if you're curious how this concept might apply to the real world.

## Practice

Problem 1
Evaluate the expression 7, plus, 4, b when b, equals, 3.

Want more practice like this? Check out this basic exercise and this more advanced exercise.