Precalculus (10th Edition)

Published by Pearson
ISBN 10: 0-32197-907-9
ISBN 13: 978-0-32197-907-0

Appendix A - Review - A.6 Solving Equations - A.6 Assess Your Understanding - Page A52: 101

Answer

$\left\{\dfrac{-1- \sqrt{5}}{4},\dfrac{-1+ \sqrt{5}}{4}\right\}$

Work Step by Step

Add $2x-1$ to both sides. $4x^2+2x-1=1-2x+2x-1$ Simplify. $4x^2+2x-1=0$ The equation is in standard form $ax^2+bx+c=0$. We have $a=4,b=2$ and $c=-1$. The discriminant is $=b^2-4ac$ $=(2)^2-4(4)(-1)$ $=4+16$ $=20$ Since $20<0$. There are two real solutions. The quadratic formula is $x=\dfrac{-b\pm \sqrt{b^2-4ac}}{2a}$ Substitute the values.of $a, b, c, $ and the discriminant to obtain: $x=\dfrac{-(2)\pm \sqrt{(20)}}{2(4)}$ Simplify. $x=\dfrac{-2\pm 2\sqrt{5}}{8}$ Factor out $2$. $x=\dfrac{2(-1\pm \sqrt{5})}{8}$ Simplify. $x=\dfrac{-1\pm \sqrt{5}}{4}$ Hence, the solution set is $\left\{\dfrac{-1- \sqrt{5}}{4},\dfrac{-1+ \sqrt{5}}{4}\right\}$.
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