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MathNet 2021 — Part 04 Question 21

Math Olympiad Vault · MathNet 2021 — Part 04

Question 21

Let $a$ and $b$ be positive integers with $a \gt b$. Suppose that
$$
\sqrt{\sqrt{a} + \sqrt{b}} + \sqrt{\sqrt{a} - \sqrt{b}}
$$
is an integer.

a. Must $\sqrt{a}$ be an integer?

b. Must $\sqrt{b}$ be an integer?