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: 53

Answer

$\dfrac{5\sqrt3+\sqrt 6}{23}$

Work Step by Step

Rationalize the denominator by multiplying $5+\sqrt2$ to both the numerator and the denominator: $\dfrac{\sqrt 3}{5-\sqrt 2}\\ =\dfrac{\sqrt 3}{5-\sqrt 2} \cdot \dfrac{5+\sqrt 2}{5+\sqrt 2}$ Use special formula $(a-b)(a+b)=a^2-b^2$ in the denominator. $=\dfrac{\sqrt 3(5+\sqrt 2)}{5^2-(\sqrt 2)^2}$ $=\dfrac{\sqrt 3(5+\sqrt 2)}{25-2}$ $=\dfrac{\sqrt 3(5+\sqrt 2)}{23}$ Use the distributive property: $=\dfrac{5\sqrt3+\sqrt 2\cdot \sqrt3}{23}$ $=\dfrac{5\sqrt3+\sqrt {2(3)}}{23}$ $=\dfrac{5\sqrt3+\sqrt6}{23}$ Hence, the correct answer is $\frac{5\sqrt3+\sqrt 6}{23}$.
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