Elementary and Intermediate Algebra: Concepts & Applications (6th Edition)

Published by Pearson
ISBN 10: 0-32184-874-8
ISBN 13: 978-0-32184-874-1

Chapter 11 - Quadratic Functions and Equations - 11.2 The Quadratic Formula - 11.2 Exercise Set - Page 713: 28


$x=-\displaystyle \frac{7}{6}$

Work Step by Step

$ 36x^{2}+84x+49=0\qquad$... solve with the Quadractic formula. $a=36,\ b=84,\ c=49$ $ x=\displaystyle \frac{-b\pm\sqrt{b^{2}-4ac}}{2a}\qquad$... substitute $b$ for $84,\ a$ for $36$ and $c$ for $49$. $ x=\displaystyle \frac{-84\pm\sqrt{(84)^{2}-4\cdot(36)\cdot 49}}{2\cdot 36}\qquad$... simplify. $x=\displaystyle \frac{-84\pm\sqrt{7056-7056}}{72}$ $x=\displaystyle \frac{-84\pm\sqrt{0}}{72}$ $x=\displaystyle \frac{-84}{72}$ $x=-\displaystyle \frac{7}{6}$
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