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\(a\) is the product of \(3\) and the square root of \(2,\) \(b\) is the product of \(2\) and the square root of \(3,\)

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\(a\) is the product of \(3\) and the square root of \(2,\) \(b\) is the product of \(2\) and the square root of \(3,\) and \(c\) is the product of \(2\) and the square root of \(6.\) If \(x\) is the square of the sum of \(a\) and \(b,\) \(y\) is the product of \(6\) and the difference of \(5\) and \(c,\) and \(z\) is the product of \(2\) squared and \(3\) squared, what is \(\dfrac{xy}{z} ?\)

A. \(1\)

B. \(30-12\sqrt6\)

C. \(36\)

D. \(30+12\sqrt6\)

E. \(64\)

Answer: A

Source: Princeton Review
Source: — Problem Solving |

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Vincen wrote:
Mon Sep 07, 2020 7:21 am
\(a\) is the product of \(3\) and the square root of \(2,\) \(b\) is the product of \(2\) and the square root of \(3,\) and \(c\) is the product of \(2\) and the square root of \(6.\) If \(x\) is the square of the sum of \(a\) and \(b,\) \(y\) is the product of \(6\) and the difference of \(5\) and \(c,\) and \(z\) is the product of \(2\) squared and \(3\) squared, what is \(\dfrac{xy}{z} ?\)

A. \(1\)

B. \(30-12\sqrt6\)

C. \(36\)

D. \(30+12\sqrt6\)

E. \(64\)

Answer: A

Source: Princeton Review
If \(x\) is the square of the sum of \(a\) and \(b = (3\sqrt{2}+2\sqrt{3})^2=18+12\sqrt{6}+12=30+12\sqrt{6}\)

\(y\) is the product of \(6\) and the difference of \(5\) and \(c = 6\cdot (5-2\sqrt{6})=30-12\sqrt{6}\)

And \(z\) is the product of \(2\) squared and \(3\) squared, \(= 2^2\cdot 3^2=36\)

What is \(\dfrac{xy}{z}=\dfrac{(30+12\sqrt{6})\cdot (30-12\sqrt{6})}{36}=\dfrac{900+360\sqrt{6}-360\sqrt{6}-864}{36}=\dfrac{36}{36}=1\)