Algebra: A Combined Approach (4th Edition)

Published by Pearson
ISBN 10: 0321726391
ISBN 13: 978-0-32172-639-1

Chapter 4 - Cumulative Review - Page 333: 30

Answer

The ordered pair $(-2,-4)$ is the solution of the system.

Work Step by Step

Equation 1: $3x - 4y = 10$ Equation 2: $y = 2x$ Substitute equation 2 to equation 1: $$3x - 4y = 10$$ $$3x - 4(2x) = 10$$ $$3x - 8x = 10$$ $$-5x = 10$$ Divide both sides by $-5$: $$\frac{-5x}{-5} = \frac{10}{-5}$$ $$x=-2$$ Substitute this value to equation 1: $$3x - 4y = 10$$ $$3(-2) - 4y = 10$$ $$-6 - 4y = 10$$ Add $6$ to both sides: $$-6+6 - 4y = 10+6$$ $$- 4y = 16$$ Divide both sides by $-4$: $$\frac{-4y}{-4} = \frac{16}{-4}$$ $$y=-4$$ Check using equation 2: $$y=2x$$ $$-4=2(-2)$$ $$-4=-4$$ Therefore, the ordered pair $(-2,-4)$ is the solution of the system.
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