Algebra: A Combined Approach (4th Edition)

Published by Pearson
ISBN 10: 0321726391
ISBN 13: 978-0-32172-639-1

Chapter 11 - Test - Page 832: 5


$x_{1}=-\dfrac{1}{7}$ and $x_{2}=-1$

Work Step by Step

Given $7x^2+8x+1=0$ $a=7, \ b=8, \ c=1$ Using the quadratic formula: $\dfrac{-b\pm \sqrt{b^2-4ac}}{2a} , $ we have: $\dfrac{-8\pm \sqrt{(8)^2-4\times 7\times 1}}{2\times 7} = \dfrac{-8\pm \sqrt{64-28}}{14} = \dfrac{-8\pm \sqrt{36}}{14} = \dfrac{-8\pm 6}{14}$ Therefore the solutions are $x_{1}=\dfrac{-8 + 6}{14}=\dfrac{-2}{14}=-\dfrac{1}{7}$ and $x_{2}=\dfrac{-8 - 6}{14}=\dfrac{-14}{14}=-1$
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