1973 AHSME Problems/Problem 13

Revision as of 16:31, 27 July 2018 by Rockmanex3 (talk | contribs) (Solution to Problem 13 (credit to gaussintraining))
(diff) ← Older revision | Latest revision (diff) | Newer revision → (diff)

Problem

The fraction $\frac{2(\sqrt2+\sqrt6)}{3\sqrt{2+\sqrt3}}$ is equal to

$\textbf{(A)}\ \frac{2\sqrt2}{3} \qquad \textbf{(B)}\ 1 \qquad \textbf{(C)}\ \frac{2\sqrt3}3 \qquad \textbf{(D)}\ \frac43 \qquad \textbf{(E)}\ \frac{16}{9}$

Solution

Squaring the expression and taking the positive square root (since numerator and denominator are positive) of the result yields \[\sqrt{(\frac{2(\sqrt2+\sqrt6)}{3\sqrt{2+\sqrt3}})^2}\] \[\sqrt{\frac{4(2+4\sqrt{3}+6)}{9(2+\sqrt{3}}}\] \[\sqrt{\frac{4(8+4\sqrt{3})}{9(2+\sqrt{3}}}\] \[\sqrt{\frac{16}{9}}\] \[\frac43\]

The answer is $\boxed{\textbf{(D)}}$.

See Also

1973 AHSC (ProblemsAnswer KeyResources)
Preceded by
Problem 12
Followed by
Problem 14
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35
All AHSME Problems and Solutions