College Algebra (10th Edition)

Published by Pearson
ISBN 10: 0321979478
ISBN 13: 978-0-32197-947-6

Chapter 8 - Section 8.1 - Systems of Linear Equations: Substitution and Elimination - 8.1 Assess Your Understanding - Page 555: 41

Answer

$x = \frac 15$ and $y = \frac 13$

Work Step by Step

If $u = \frac{1}{x}$ and $v = \frac{1}{y}$, the system can be written as: $u + v = 8$ $3u - 5v = 0$ 1. Solve for $u$ in the first equation: $u + v = 8$ Subtract v from both sides. $u = 8 - v$ 2. Substitute this value into the second equation, and solve for v: $3u - 5v = 0$ $3(8-v) - 5v = 0$ $24 - 3v - 5v = 0$ $24 - 8v = 0$ Add 8v to both sides. $24 = 8v$ Divide both sides by 3: $3 = v$ 3. Find the value of $u$: $u = 8 -v = 8 -3 = 5$ 4. Calculate x and y $\frac 1x = u $ $\frac 1u = x$ $\frac 1 {5} = x$ $\frac 1y = v$ $\frac 1v = y$ $\frac 13 = y$
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