Elementary Algebra

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

Chapter 9 - Roots and Radicals - 9.2 - Simplifying Radicals - Problem Set 9.2: 60

Answer

$-17\sqrt{10}$

Work Step by Step

Using the properties of radicals, the given expression, $ 2\sqrt{40}-7\sqrt{90} ,$ simplifies to \begin{array}{l}\require{cancel} 2\sqrt{4\cdot10}-7\sqrt{9\cdot10} \\\\= 2\sqrt{(2)^2\cdot10}-7\sqrt{(3)^2\cdot10} \\\\= 2\cdot2\sqrt{10}-7\cdot3\sqrt{10} \\\\= 4\sqrt{10}-21\sqrt{10} \\\\= -17\sqrt{10} .\end{array}
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