Algebra 2 (1st Edition)

Published by McDougal Littell
ISBN 10: 0618595414
ISBN 13: 978-0-61859-541-9

Chapter 4 Quadratic Functions and Factoring - 4.5 Solve Quadratic Equations by Finding Square Roots - 4.5 Exercises - Skill Practice - Page 270: 28


The solutions are $\sqrt{5} $ and $-\sqrt{5}.$

Work Step by Step

$ 7r^{2}-10=25\qquad$ ...add $10$ to each side. $ 7r^{2}-10+10=25+10\qquad$ ...simplify. $ 7r^{2}=35\qquad$ ...divide each side with $7$ $ r^{2}=5\qquad$ ...take square roots of each side. $\sqrt{r^{2}}=\sqrt{5}\qquad$ ...simplify. ...When solving an equation of the form $x^{2}=s$ where $s>0$, we find both the positive and negative solutions. $r=\pm\sqrt{5}$
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