Elementary Algebra

Published by Cengage Learning
ISBN 10: 1285194055
ISBN 13: 978-1-28519-405-9

Chapter 10 - Quadratic Equations - Chapter 10 Test - Page 469: 23


14 mph

Work Step by Step

Recall that velocity is equal to change in distance over change in time. We call t the time it takes Abu. Thus, we obtain: $\frac{72}{t+2} = \frac{ 56}{t} -2 $ We create common denominators and solve for t: $ \frac{72t}{t(t+2)} = \frac{56(t+2)}{t(t+2)} + \frac{-2t(t+2)}{t(t+2)}$ Since the denominators are the same, we cancel them out and solve. (Recall, t cannot be negative.) $ 0 = -2t^2 -20t + 112 \\ 2(t-4)(t+14) \\ t =4 $ Thus, we find the velocity: $v_{Abu} = 56/4 =14$ mph
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