Elementary and Intermediate Algebra: Concepts & Applications (6th Edition)

Published by Pearson
ISBN 10: 0-32184-874-8
ISBN 13: 978-0-32184-874-1

Chapter 11 - Quadratic Functions and Equations - Mid-Chapter Review - Mixed Review - Page 733: 13


$x=5$ or $x=-6$

Work Step by Step

$(t+4)(t-3)=18\qquad$...apply the FOIL method. $ t^{2}-3t+4t-12=18\qquad$...simplify. $ t^{2}+t-12=18\qquad$... add $-18$ to both sides. $ t^{2}+t-30\qquad$... solve with the Quadratic formula. $x=\displaystyle \frac{-b\pm\sqrt{b^{2}-4ac}}{2a}$ $x=\displaystyle \frac{-1\pm\sqrt{1+120}}{2}$ $x=\displaystyle \frac{-1\pm\sqrt{121}}{2}$ $x=\displaystyle \frac{-1\pm 11}{2}$ $x=\displaystyle \frac{-1+11}{2}=\frac{10}{2}=5$ or $x=\displaystyle \frac{-1-11}{2}=\frac{-12}{2}=-6$
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