Big Ideas Math - Algebra 1, A Common Core Curriculum

Published by Big Ideas Learning LLC
ISBN 10: 978-1-60840-838-2
ISBN 13: 978-1-60840-838-2

Chapter 9 - Solving Quadratic Equations - 9.5 - Solving Quadratic Equations Using the Quadratic Formula - Exercises - Page 521: 21

Answer

$x=-\frac{1}{2}$ and $x=-4$.

Work Step by Step

$2x^{2}+9x+7=3\implies 2x^{2}+9x+4=0$ Comparing $2x^{2}+9x+4=0$ with $ax^{2}+bx+c=0$, we get $a=2$, $b=9$ and $c=4$. The quadratic formula is $x=\frac{-b \pm \sqrt {b^{2}-4ac}}{2a}$ Substituting the values, we get $x=\frac{-(9) \pm \sqrt {(9)^{2}-4(2)(4)}}{(2)(2)}=\frac{-9\pm 7}{4}$ The solutions of the equation are $x=\frac{-9+7}{4}=-\frac{1}{2}$ and $x= \frac{-9-7}{4}=-4$
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