Algebra 2 Common Core

Published by Prentice Hall
ISBN 10: 0133186024
ISBN 13: 978-0-13318-602-4

Chapter 4 - Quadratic Functions and Equations - 4-9 Quadratic Systems - Practice and Problem-Solving Exercises - Page 262: 17

Answer

The solution is $(1, -2)$.

Work Step by Step

We will use substitution to solve this system of equations. We substitute one of the expressions for $y$, which would mean that we are going to set the two equations equal to one another to solve for $x$ first: $2x^2 - 3x - 1 = x - 3$ We want to move all terms to the left side of the equation. $2x^2 - 3x - x - 1 + 3 = 0$ Combine like terms: $2x^2 - 4x + 2 = 0$ Factor out any common terms: $2(x^2 - 2x + 1) = 0$ Divide each side by $2$: $x^2 - 2x + 1 = 0$ Factor the quadratic equation. The quadratic equation takes the form $ax^2 + bx + c = 0$. We need to find factors whose product is $ac$ but sum up to $b$. In this exercise, $ac = 1$ and $b = -2$. The factors $-1$ and $-1$ will work: $(x - 1)(x - 1) = 0$ Use the Zero-Product Property by equating each unique factor to $0$, then solve each equation. $x - 1 = 0$ Add $1$ to each side of the equation: $x = 1$ Now that we have the possible value for $x$, we can plug them into one of the original equations to find the corresponding $y$ value. Let's use the second equation: $y = x - 3$ Substitute the solution $1$ for $x$: $y = 1 - 3$ Subtract to solve: $y = -2$ The solution is $(1, -2)$.
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