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 1-14 - Cumulative Review - Final Exam - Page 931: 48

Answer

$x_{1}=-2+\sqrt7$ $x_{2}=-2-\sqrt7$

Work Step by Step

We have to solve the quadratic equation $$x^2+4x=3.$$ Let's rewrite it in the standard form: $$x^2+4x-3=0.$$ Let's find the discriminant. $$D=b^2-4ac=4^2-4\cdot1\cdot(-3)=28>0.$$ Because the discriminant is positive we have two solutions. We determine them using the Quadratic Formula: $x_{1}=\dfrac{-b+\sqrt D}{2a}=\dfrac{-4+\sqrt{28}}{2}=-2+\dfrac{\sqrt{4\cdot7}}{2}=-2+\sqrt7$ $x_{2}=\dfrac{-b-\sqrt D}{2a}=\dfrac{-4-\sqrt{28}}{2}=-2-\dfrac{\sqrt{4\cdot7}}{2}=-2-\sqrt7$
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