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: 29

Answer

The solution of the system will be ordered pair $(6,\frac{1}{2})$.

Work Step by Step

Equation 1: $x + 2y = 7$ Equation 2: $2x + 2y = 13$ Multiply equation 2 by $-1$: $$[2x + 2y = 13]\cdot-1$$ $$-2x - 2y = -13$$ Add this equation to equation 1: $$-2x - 2y = -13$$ $$+$$ $$x + 2y = 7$$ $$=$$ $$-x=-6$$ $$x=6$$ Substitute this value to equation 1: $$x + 2y = 7$$ $$6 + 2y = 7$$ Subtract $6$ from both sides: $$6 -6+ 2y = 7-6$$ $$2y=1$$ Divide both sides by $2$: $$\frac{2y}{2}=\frac{1}{2}$$ $$y=\frac{1}{2}$$ Check using equation 2: $$2x + 2y = 13$$ $$2(6) + 2(\frac{1}{2}) = 13$$ $$12+1=13$$ $$13=13$$ Therefore, the solution of the system will be ordered pair $(6,\frac{1}{2})$.
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