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MathNet 2009-part-03 — 175 problems (EN–VI) Question 174

Math Olympiad Vault · MathNet 2009-part-03 — 175 problems (EN–VI)

Question 174

a. Prove: if $a - \frac{1}{b} + b\left(b + \frac{3}{a}\right)$ is an integer for some positive integers $a$ and $b$, then it is a perfect square.

b. Find two integers $a$ and $b$ such that $a - \frac{1}{b} + b\left(b + \frac{3}{a}\right)$ is a positive integer but not a perfect square.