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Exercises Expressions, exponents and radicals

Example 9 from Algebra and Trigonometry, 1.1 Real Numbers: Algebra Essentials

Evaluating an Algebraic Expression at Different Values

Evaluate the expression $2 x - 7$ for each value for x.

ⓐ $x = 0$
ⓑ $x = 1$
ⓒ $x = \frac{1}{2}$
ⓓ $x = −4$

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.

1
Solution
1. ⓐ Substitute 0 for $x .$
  $\begin{matrix} 2 x - 7 & = & 2 (0) - 7 \\ = & 0 - 7 \\ = & −7 \end{matrix}$
2. ⓑSubstitute 1 for $x .$
  $\begin{matrix} 2 x - 7 & = & 2 (1) - 7 \\ = & 2 - 7 \\ = & −5 \end{matrix}$
3. ⓒ Substitute $\frac{1}{2}$ for $x .$
  $\begin{matrix} 2 x - 7 & = & 2 (\frac{1}{2}) - 7 \\ = & 1 - 7 \\ = & −6 \end{matrix}$
4. ⓓSubstitute $−4$ for $x .$
  $\begin{matrix} 2 x - 7 & = & 2 (- 4) - 7 \\ = & - 8 - 7 \\ = & −15 \end{matrix}$

Your turn

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

Evaluate the expression $11 - 3 y$ for each value for y.

ⓐ $y = 2$
ⓑ $y = 0$
ⓒ $y = \frac{2}{3}$
ⓓ $y = −5$

How did it go?

PreviousDescribing Algebraic Expressions Next Evaluating Algebraic Expressions

From Algebra and Trigonometry (1st edition) by OpenStax (Rice University), section 1.1, 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.