Precalculus (10th Edition)

Published by Pearson
ISBN 10: 0-32197-907-9
ISBN 13: 978-0-32197-907-0

Appendix A - Review - A.10 nth Roots; Rational Exponents - A.10 Assess Your Understanding - Page A88: 38

Answer

$-1+\sqrt 5 $

Work Step by Step

Multiply using the FOIL (first, outer, inner, last) method: $(\sqrt 5-2)(\sqrt 5+3)=\sqrt 5 \cdot \sqrt 5+3\cdot \sqrt 5-2\cdot \sqrt 5- 2\cdot 3$ Simplify. $=(\sqrt 5)^2+3\sqrt 5-2 \sqrt 5- 6$ $=5+3\sqrt 5-2 \sqrt 5-6$ $=-1+3\sqrt 5-2 \sqrt 5$ Factor out $\sqrt{5}$ then simplify. $=-1+\sqrt 5(3-2) $ $=-1+\sqrt 5(1) $ $=-1+\sqrt 5 $ Hence, the correct answer is $-1+\sqrt 5 $.
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