Intermediate Algebra (6th Edition)

Published by Pearson
ISBN 10: 0321785045
ISBN 13: 978-0-32178-504-6

Chapter 4 - Section 4.1 - Solving Systems of Linear Equations in Two Variables - Exercise Set - Page 212: 20

Answer

Ordered pair solution $(2,-9)$

Work Step by Step

We have $$(1) \frac{2}{5}x+\frac{1}{5}y=-1$$ $$(2)x+\frac{2}{5}y=-\frac{8}{5}$$ From (2) $$(3)x = -\frac{8}{5}-\frac{2}{5}y$$ Substituting (3) in (1) $$\frac{2}{5}(-\frac{8}{5}-\frac{2}{5}y)+\frac{1}{5}y= -1$$ $$-\frac{16}{25}-\frac{4}{25}y+\frac{1}{5}y= -1$$ $$\frac{1}{25}y=\frac{-9}{25}$$ $$y = \frac{-9*25}{25} = -9$$ Solving for $x$ $$x = -\frac{8}{5}-\frac{2}{5}*(-9) = 2$$ Ordered pair solution $(2,-9)$
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