Finite Math and Applied Calculus (6th Edition)

Published by Brooks Cole
ISBN 10: 1133607705
ISBN 13: 978-1-13360-770-0

Chapter 3 - Review - Review Exercises - Page 219: 9

Answer

- The solution is: $(x , \frac {2}{3}x)$; x arbitrary, or $(\frac {3} 2 y, y)$; y arbitrary.

Work Step by Step

1. Notice that, if we add the two equations, neither $x$ or $y$ will be eliminated. But, if we multiply the first equation by -12, the $x$ unknown will be eliminated: $-12(\frac 1 2x - \frac 3 4y) = -12(0) $ $6x - 9y = 0$ $-6x + 9y = 0$ $6x - 9y = 0$ Adding the equations: $-6x + 6x + 9y - 9y = 0$ $0 = 0$ 2. Apparently, the system is redundant. So, solve for $y$ and for $x$ in the second equation: $6x - 9y = 0$ $6x = 9y$ $\frac 6 9 x = \frac 9y 9$ $\frac 2 3 x = y$ - Solving for $x$: $6x = 9 y$ $\frac {6x} 6 = \frac {9y} 6$ $x = \frac {3y} 2$ - Therefore, the solution is: $(x , \frac {2}{3}x)$; x arbitrary, or $(\frac {3} 2 y, y)$; y arbitrary.
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