Answer
$21-4\sqrt 5$
Work Step by Step
$(2\sqrt 5-1)^{2}$
=$(2\sqrt 5-1)(2\sqrt 5-1)$
=$2\sqrt 5(2\sqrt 5-1)-1(2\sqrt 5-1)$
=$(2\sqrt 5)^{2}-2\sqrt 5-2\sqrt 5+1$
=$4(5)-4\sqrt 5+1$
=$20-4\sqrt 5+1$
=$21-4\sqrt 5$
Algebra: A Combined Approach (4th Edition)
by Martin-Gay, Elayn
Published by
Pearson
ISBN 10:
0321726391
ISBN 13:
978-0-32172-639-1
Chapter 13 - Cumulative Review - Page 970: 42
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