Algebra: A Combined Approach (4th Edition)

Published by Pearson
ISBN 10: 0321726391
ISBN 13: 978-0-32172-639-1

Chapter 11 - Section 11.3 - Integrated Review - Summary on Solving Quadratic Equations - Page 791: 14


$x_{1}= 3i$ and $x_{2} = -3i$

Work Step by Step

Given $2x^2+18=0$ $a= 2, \ b=0, \ c=18$ Using the quadratic formula: $\dfrac{-b \pm \sqrt{b^2-4ac}}{2a}$ we have: $\dfrac{-0 \pm \sqrt{0^2-4 \times 2\times 18}}{2 \times 2} = \dfrac{\pm \sqrt{-144}}{4} = \dfrac{\pm \sqrt{144}i}{4} = \dfrac{\pm \sqrt{12^2}i}{4} = \dfrac{\pm 12i}{4} = \pm 3i$ Therefore the solutions are $x_{1}= 3i$ and $x_{2} = -3i$
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