Algebra: A Combined Approach (4th Edition)

Published by Pearson
ISBN 10: 0321726391
ISBN 13: 978-0-32172-639-1

Chapter 7 - Section 7.1 - Simplifying Rational Expressions - Exercise Set - Page 489: 7


a) \$403 b) \$7 c) The average cost decreases when more DVDs are produced. This is illustrated by parts (a) and (b) - the cost is much less when we produce 100 DVDs than when we produce 1 DVD.

Work Step by Step

a) $x$ represents the number of DVDs. To calculate the average cost for 1 DVD, we plug in 1 for $x$: $\frac{3x + 400}{x} = \frac{3\cdot 1 + 400}{1} = 3 + 400 = 403$ b) Once again, $x$ represents the number of DVDs. In this part we plug in 100 for $x$: $\frac{3x+400}{x} = \frac{3\cdot 100 + 400}{100} = \frac{700}{100} = 7$ c) if you graph the equation, you'll see that the graph slopes downwards when $x \gt 0$. This indicates that the average cost is decreasing.
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