Thinking Mathematically (6th Edition)

Published by Pearson
ISBN 10: 0321867327
ISBN 13: 978-0-32186-732-2

Chapter 6 - Algebra: Equations and Inequalities - 6.5 Quadratic Equations - Exercise Set 6.5 - Page 400: 69

Answer

the solution set is\[\left\{ \frac{-3\pm \sqrt{3}}{6} \right\}\].

Work Step by Step

The given equation can be written as\[6{{x}^{2}}+6x+1=0\]. Compare the given equation with the equation\[a{{x}^{2}}+bx+c=0\]. Here,\[a=6,\,\,b=6,\text{ and }c=1\]. Now put these values in the quadratic formula: \[x=\frac{-b\pm \sqrt{{{b}^{2}}-4ac}}{2a}\] That is, \[\begin{align} & x=\frac{-6\pm \sqrt{{{\left( 6 \right)}^{2}}-4\times 6\times 1}}{2\times 6} \\ & =\frac{-6\pm \sqrt{36-24}}{12} \\ & =\frac{-6\pm \sqrt{12}}{12} \\ & =\frac{-6\pm 2\sqrt{3}}{12} \end{align}\] Further simplify it to get, \[\begin{align} & x=\frac{-6\pm 2\sqrt{3}}{12} \\ & =2\left( \frac{-3\pm \sqrt{3}}{12} \right) \\ & =\frac{-3\pm \sqrt{3}}{6} \end{align}\] Hence, the solution set is\[\left\{ \frac{-3\pm \sqrt{3}}{6} \right\}\].
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