Big Ideas Math - Algebra 1, A Common Core Curriculum

Published by Big Ideas Learning LLC
ISBN 10: 978-1-60840-838-2
ISBN 13: 978-1-60840-838-2

Chapter 9 - Solving Quadratic Equations - 9.6 - Solving Nonlinear Systems of Equations - Exercises - Page 530: 13

Answer

The solutions are $(0,-5)$ and $(-3,-8)$.

Work Step by Step

The given system is $y=x-5$ ...... (1) $y=x^2+4x-5$ ...... (2) Substitute $x-5$ for $y$ in equation (2). $\Rightarrow x-5=x^2+4x-5$ Add $5-x$ to each side. $\Rightarrow x-5+5-x=x^2+4x-5+5-x$ Simplify. $\Rightarrow 0=x^2+3x$ Factor out $x$. $\Rightarrow 0=x(x+3)$ Use zero product property. $\Rightarrow x=0$ or $x+3=0$ Solve for $x$. $\Rightarrow x=0$ or $x=-3$ Substitute $0$ for $x$ in equation (1). $\Rightarrow y=0-5$ Simplify. $\Rightarrow y=-5$ Substitute $-3$ for $x$ in equation (1). $\Rightarrow y=-3-5$ Simplify. $\Rightarrow y=-8$ Hence, the solutions are $(0,-5)$ and $(-3,-8)$.
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