College Algebra (6th Edition)

Published by Pearson
ISBN 10: 0-32178-228-3
ISBN 13: 978-0-32178-228-1

Chapter 5 - Systems of Equations and Inequalities - Exercise Set 5.4 - Page 559: 28

Answer

$\{\ (0,-4),\ (2\sqrt{3},2),\ (-2\sqrt{3},2)\ \}$

Work Step by Step

1. Eliminating: Eliminate the $( x^{2})$ terms: $\left\{\begin{array}{lll} x^{2}-2y=8 & , & / \times(-1)\\ x^{2}+y^{2}=16 & , & / add \end{array}\right.$ $y^{2}+2y=8$ 2. Solving: $(y+4)(y-2)=0$ $y+4=0$ or $y-2=0$ $y=-4$ or $y=2$ 3. Back-substituting into $x^{2}-2y=8$ $\left[\begin{array}{lll} y=-4 & or & y=2\\ x^{2}-2(-4)=8 & & x^{2}-2(2)=8 \\ x^{2}=8-8 & & x^{2}=8+4\\ x^{2}=0 & & x^{2}=12\\ x=0 & & x=\pm\sqrt{12}\\ & & x=\pm 2\sqrt{3} \end{array}\right]$ The solution set is $\{\ (0,-4),\ (2\sqrt{3},2),\ (-2\sqrt{3},2)\ \}$
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