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Exercises Expressions, exponents and radicals

Example 2.18 from Prealgebra, 2.2 Evaluate, Simplify, and Translate Expressions

Evaluate, Simplify, and Translate Expressions: example 2.18

$Evaluate 2 x^{2} + 3 x + 8 when x = 4 .$

Work it out on paper first. Then open the solution one step at a time, and stop as soon as you can finish on your own.

Solution
We need to be careful when an expression has a variable with an exponent. In this expression, $2 x^{2}$ means $2 \cdot x \cdot x$ and is different from the expression ${(2 x)}^{2},$ which means $2 x \cdot 2 x .$

Simplify $4^{2}$ .

Multiply.

Add.

Your turn

The book's Try It right after this example: same idea, new numbers. Only the answer is given.

Evaluate:

$3 x^{2} + 4 x + 1 when x = 3 .$

How did it go?

PreviousEvaluate, Simplify, and Translate Expressions: example 2.17 Next Evaluate, Simplify, and Translate Expressions: example 2.19

From Prealgebra (1st edition) by OpenStax (Rice University), section 2.2, licensed under CC BY 4.0. Original at openstax.org. We split the solution into steps; the words, numbers and figures are the book's. OpenStax doesn't endorse this site.