College Algebra 7th Edition

Published by Brooks Cole
ISBN 10: 1305115546
ISBN 13: 978-1-30511-554-5

Chapter 5, Systems of Equations and Inequalities - Section 5.4 - Systems of Nonlinear Equations - 5.4 Exercises - Page 465: 3

Answer

$(4, 16)$ and $(-3, 9)$

Work Step by Step

We will use the substitution method to solve this system of equations because one of the equations already has one variable, $y$, isolated. We will use this expression to substitute into the second equation: $y = x + 12$ $x^{2} = x + 12$ Bring all terms to the left-hand side to set the equation equal to $0$ to turn it into a quadratic equation: $x^{2} - x - 12 = 0$ $(x - 4)(x + 3) = 0$ Now, set each factor equal to $0$ to solve for $x$: $x - 4 = 0$ or $x + 3 = 0$ $x = 4$ or $ x = -3$ Now that we have the values for $x$, we can then plug these values into one of the equations to solve for $y$. Let's use the second equation to make it easier: $y = x + 12$ $y = (4) + 12$ $y = 16$ $y = x + 12$ $y = (-3) + 12$ $y = 9$ The points where these two equations (graphs) intersect are $(4, 16)$ and $(-3, 9)$.
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