Algebra 2 Common Core

Published by Prentice Hall
ISBN 10: 0133186024
ISBN 13: 978-0-13318-602-4

Chapter 6 - Radical Functions and Rational Exponents - Chapter Review - Page 424: 33

Answer

$\dfrac{9+3\sqrt2}{7}$

Work Step by Step

Simplify each radical to obtain: \begin{align*} &=\dfrac{3+\sqrt{9(2)}}{1+\sqrt{4(2)}}\\\\ &=\dfrac{3+\sqrt{3^2(2)}}{1+\sqrt{2^2(2)}}\\\\ &=\dfrac{3+3\sqrt2}{1+2\sqrt2} \end{align*} Rationalize the denominator by multiplying $1-2\sqrt2$ to both the numerator and denominator to obtain: \begin{align*} &=\dfrac{3+3\sqrt2}{1+2\sqrt2}\cdot \dfrac{1-2\sqrt2}{1-2\sqrt2}\\\\ \end{align*} Recall: $(a+b)(a-b) = a^2-b^2$ Use the rule above with $a=1$ and $b=2\sqrt{2}$ to obtain: \begin{align*} \dfrac{3+3\sqrt2}{1+2\sqrt2}\cdot \dfrac{1-2\sqrt2}{1-2\sqrt2}&=\dfrac{(3+3\sqrt2)(1-2\sqrt2)}{1^2-(2\sqrt2)^2}\\\\ &=\dfrac{(3+3\sqrt2)(1-2\sqrt2)}{1^2-(2\sqrt2)^2}\\\\ &=\dfrac{(3+3\sqrt2)(1-2\sqrt2)}{1-2^2(\sqrt2)^2)}\\\\ &=\dfrac{(3+3\sqrt2)(1-2\sqrt2)}{1-4(2)}\\\\ &=\dfrac{(3+3\sqrt2)(1-2\sqrt2)}{1-8}\\\\ &=\dfrac{(3+3\sqrt2)(1-2\sqrt2)}{-7}\\\\ \end{align*} Recall: $(a+b)(c+d)=a(c+d)+b(c=+)$ Use the rule above to simplify the numerator and obtain: \begin{align*} \dfrac{(3+3\sqrt2)(1-2\sqrt2)}{-7}&=\dfrac{3(1-2\sqrt2)+3\sqrt2(1-2\sqrt2)}{-7}\\\\ &=\dfrac{3(1)-3(2\sqrt2)+3\sqrt2(1)-3\sqrt2(2\sqrt2)}{-7}\\\\ &=\dfrac{3-6\sqrt2+3\sqrt2-6\sqrt4}{-7}\\\\ &=\dfrac{3-6\sqrt2+3\sqrt2-6(2)}{-7}\\\\ &=\dfrac{3-6\sqrt2+3\sqrt2-12}{-7}\\\\ \end{align*} Combine like terms to obtain: \begin{align*} &=\dfrac{(3-12)+(-6\sqrt2+3\sqrt2)}{-7}\\\\ &=\dfrac{-9+(-6+3)(\sqrt2)}{-7}\\\\ &=\dfrac{-9+(-3)(\sqrt2)}{-7}\\\\ &=\dfrac{-9-3\sqrt2}{-7}\\\\ &=\dfrac{-(9+3\sqrt2)}{-7}\\\\ &=\dfrac{9+3\sqrt2}{7} \end{align*}
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