Thinking Mathematically (6th Edition)

Published by Pearson
ISBN 10: 0321867327
ISBN 13: 978-0-32186-732-2

Chapter 5 - Number Theory and the Real Number System - 5.4 The Irrational Numbers - Exercise Set 5.4 - Page 296: 59



Work Step by Step

Rationalize the denominator by multiplying $\sqrt7$ to both the numerator and the denominator: $=\dfrac{21\sqrt7}{\sqrt7(\sqrt7)} \\=\dfrac{21\sqrt7}{7} \\=3\sqrt7$
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