1986 AIME Problems/Problem 1

Revision as of 18:51, 28 October 2006 by Nebula42 (talk | contribs) (Solution)

Problem

What is the sum of the solutions to the equation $\sqrt[4]{x} = \frac{12}{7 - \sqrt[4]{x}}$?

Solution

Let $y = \sqrt[4]{x}$. Then we have $\displaystyle y(7 - y) = 12$, or, by simplifying, $\displaystyle y^2 - 7y + 12 = (y - 3)(y - 4) = 0$. This means that $\sqrt[4]{x} = y = 3$ or $\displaystyle 4$. Thus the sum of the possible solutions for $\displaystyle x$ is $\displaystyle 4^4 + 3^4 = 337$, the answer.

See also