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: 38

Answer

$(2,2), (2,4)$

Work Step by Step

We are given the system: $\begin{cases} x^2-y^2-4x+6y-4=0\\ x^2+y^2-4x-6y+12=0 \end{cases}$ We will use the addition method. We add Equation 2 to Equation 1 to eliminate $y$ and determine $x$: $x^2-y^2-4x+6y-4+x^2+y^2-4x-6y+12=0+0$ $2x^2-8x+8=0$ $2(x^2-4x+4)=0$ $2(x-2)^2=0$ $x-2=0\Rightarrow x=2$ Substitute the value of $x$ in Equation 1 to determine $y$: $x^2-y^2-4x+6y-4=0$ $2^2-y^2-4(2)+6y-4=0$ $4-y^2-8+6y-4=0$ $-y^2+6y-8=0$ $y^2-6y+8=0$ $y^2-2y-4y+8=0$ $y(y-2)-4(y-2)=0$ $(y-2)(y-4)=0$ $y-2=0\Rightarrow y_1=2$ $y-4=0\Rightarrow y_2=4$ The system's solutions are: $(2,2), (2,4)$
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