Algebra 2 Common Core

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

Chapter 1 - Expressions, Equations, and Inequalities - 1-6 Absolute Value Equations and Inequalities - Got It? - Page 43: 3

Answer

$x = -1$

Work Step by Step

We use the definition of absolute value to rewrite the equation as two separate equations: $5x - 2 = 7x + 14\quad$ or $\quad5x - 2 = - (7x + 14)$ Use distributive property to simplify the second equation: $5x - 2 = 7x + 14\quad$ or $\quad5x - 2 = -7x - 14$ Add $2$ to both sides of the equation: $5x = 7x + 16\quad$ or $\quad5x = -7x - 12$ Subtract $7x$ from each side of the equation: $-2x = 16\quad$ or $\quad12x = -12$ Divide the first equation by $-2$ and the second equation by $12$ to isolate $x$: $x = -8\quad$ or $\quad x = -1$ Now we can check for extraneous solutions by plugging each solution back into the original equation. Let's check $x = -8$ first: $|5(-8) - 2| = 7(-8) + 14$ Multiply first: $|-40 - 2| = -56 + 14$ Add or subtract: $|-42| = -42$ This solution is extraneous because the absolute value of a number cannot be negative. Let's check $x = -1$: $|5(-1) - 2| = 7(-1) + 14$ Multiply first: $|-5 - 2| = -7 + 14$ Add or subtract: $|-7| = 7$ This is the only correct solution.
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