1955 AHSME Problems/Problem 42

Problem

If $a, b$, and $c$ are positive integers, the radicals $\sqrt{a+\frac{b}{c}}$ and $a\sqrt{\frac{b}{c}}$ are equal when and only when:

$\textbf{(A)}\ a=b=c=1\qquad\textbf{(B)}\ a=b\text{ and }c=a=1\qquad\textbf{(C)}\ c=\frac{b(a^2-1)}{a}\\ \textbf{(D)}\ a=b\text{ and }c\text{ is any value}\qquad\textbf{(E)}\ a=b\text{ and }c=a-1$


Solution

squaring, we get a + b/c = a^2 * (b/c) simplifying, a = (b/c) * (a^2-1) a / (a^2-1) = b/c (a^2-1) / a = c/b so ((a^2-1)b) / a = c

See Also

1955 AHSC (ProblemsAnswer KeyResources)
Preceded by
Problem 41
Followed by
Problem 43
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