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: 98

Answer

$\left\{-\dfrac{3}{2},-1\right\}$

Work Step by Step

The equation is in standard form $ax^2+bx+c=0$. We have $a=2,b=5$ and $c=3$. The discriminant is $=b^2-4ac$ $=(5)^2-4(2)(3)$ $=25-24$ $=1$ Since $1>0$. 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 into the quadratic formula to obtain: $x=\dfrac{-(5)\pm \sqrt{(1)}}{2(2)}$ Simplify. $x=\dfrac{-5\pm 1}{4}$ Split the expression to obtain: $x=\dfrac{-5- 1}{4}\quad $ or $\quad x=\dfrac{-5+1}{4}$ $x=\dfrac{-6}{4}\quad $ or $\quad x=\dfrac{-4}{4}$ $x=-\dfrac{3}{2}\quad $ or $\quad x=-1$ The solution set is $\left\{-\dfrac{3}{2},-1\right\}$.
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