Precalculus (6th Edition) Blitzer

Published by Pearson
ISBN 10: 0-13446-914-3
ISBN 13: 978-0-13446-914-0

Chapter 7 - Section 7.1 - Systems of Linear Equations in Two Variables - Exercise Set - Page 820: 79


a. year $ 2039$, $37$ percent. b. intersection point $(69,37)$.

Work Step by Step

a. From the first equation, we have $y=16+\frac{3}{10}x$. And the second equation gives $y=71-\frac{1}{2}x$. Let $16+\frac{3}{10}x=71-\frac{1}{2}x$; we have $\frac{4}{5}x=55$ and $x\approx69$, which corresponds to year $1970+69=2039$. At $x=69$, we have $y=16+\frac{3}{10}(69)\approx37$ percent. b. The above results are shown as the intersection point of the two lines in the graph given in the exercise, which is at about $(69,37)$.
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