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: 89

Answer

$\frac{8x^{\frac{5}{4}}}{y^{\frac{3}{4}}}$

Work Step by Step

Use $16=2^4$. $\dfrac{(16x^2y^{-\frac{1}{3}})^{\frac{3}{4}}}{(xy^2)^{\frac{1}{4}}}=\dfrac{(2^4x^2y^{-\frac{1}{3}})^{\frac{3}{4}}}{(xy^2)^{\frac{1}{4}}}$ Use the rule $\left(ab\right)^m=a^mb^m$: $=\dfrac{\left(2^4\right)^{\frac{3}{4}}\left(x^2\right)^{\frac{3}{4}}\left(y^{-\frac{1}{3}}\right)^{\frac{3}{4}}}{x^{\frac{1}{4}}\left(y^2\right)^{\frac{1}{4}}}$ Use the rule $\left(a^m\right)^n=a^{mn}$, then simplify to obtain: $=\dfrac{2^{4\cdot \frac{3}{4}}x^{2\cdot \frac{3}{4}}y^{-\frac{1}{3}\cdot \frac{3}{4}}}{x^{\frac{1}{4}}y^{2\cdot \frac{1}{4}}}$ $=\dfrac{2^3x^{ \frac{3}{2}}y^{-\frac{1}{4}}}{x^{\frac{1}{4}}y^{\frac{1}{2}}}$ $=\dfrac{8x^{ \frac{3}{2}}y^{-\frac{1}{4}}}{x^{\frac{1}{4}}y^{\frac{1}{2}}}$ Use the rule $\dfrac{a^m}{a^n} = a^{m-n}$: $=8x^{\frac{3}{2}-\frac{1}{4}}y^{-\frac{1}{4}-\frac{1}{2}}$ $=8x^{\frac{6}{4}-\frac{1}{4}}y^{-\frac{1}{4}-\frac{2}{4}}$ $=8x^{\frac{5}{4}}y^{-\frac{3}{4}}$ Use the rule $a^{-m}=\dfrac{1}{a^m}$, then simplify to obtain: $=8x^{\frac{5}{4}}\cdot \dfrac{1}{y^{\frac{3}{4}}}$ $=\dfrac{8x^{\frac{5}{4}}}{y^{\frac{3}{4}}}$ Hence, the correct answer is $\frac{8x^{\frac{5}{4}}}{y^{\frac{3}{4}}}$.
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