Basic College Mathematics (9th Edition)

Published by Pearson
ISBN 10: 0321825535
ISBN 13: 978-0-32182-553-7

Chapter 5 - Ratio and Proportion - 5.3 Proportions - 5.3 Exercises: 20

Answer

We can tell whether or not a proportion is true by cross-multiplying and checking for equality.

Work Step by Step

We can tell whether or not a proportion is true by cross-multiplying and checking for equality. For example, consider this proportion from the previous exercise: $\displaystyle \frac{30}{6}=\frac{45}{9}$ We cross-multiply: $30*9=45*6$ And check the equality: $270=270$ Since we got an identity, we know that the original proportion was true.
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