College Algebra (6th Edition)

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

Chapter 5 - Summary, Review, and Test - Review Exercises - Page 585: 31

Answer

$(1,3), (-3,-1)$

Work Step by Step

We are given the system: $\begin{cases} y=x+2\\ x^2+y^2=10 \end{cases}$ We will use the substitution method. Equation 1 is solved for $y$. Substitute the expression of $y$ in Equation 2 to eliminate $y$ and determine $x$: $\begin{cases} y=x+2\\ x^2+(x+2)^2=10 \end{cases}$ $x^2+x^2+4x+4=10$ $2x^2+4x+4-10=0$ $2x^2+4x-6=0$ $2(x^2+2x-3)=0$ $x^2+2x-3=0$ $x^2-x+3x-3=0$ $x(x-1)+3(x-1)=0$ $(x-1)(x+3)=0$ $x-1=0\Rightarrow x_1=1$ $x+3=0\Rightarrow x_2=-3$ Substitute each of the values of $x$ in the expression of $y$ to determine $y$: $y=x+2$ $x_1=1\Rightarrow y_1=1+2=3$ $x_2=-3\Rightarrow y_2=-3+2=-1$ The system's solutions are: $(1,3), (-3,-1)$
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