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MathNet 2017-part-05 — 176 problems (EN–VI) Question 42

Math Olympiad Vault · MathNet 2017-part-05 — 176 problems (EN–VI)

Question 42

Let $a$ and $n$ be two fixed positive integers.
a) Prove that there exist $n$ positive integers $a_1, a_2, \dots, a_n$ such that
$$
1 + \frac{1}{a} = \left(1 + \frac{1}{a_1}\right) \left(1 + \frac{1}{a_2}\right) \dots \left(1 + \frac{1}{a_n}\right).
$$

b) Prove that $1 + \frac{1}{a}$ has only finitely many possible representations as in the point a).