Problem

Source: Canada RepĂȘchage 2019/1 CMOQR

Tags: function, injective function, Injective, algebra, functional equation, algebra solved



A function $f$ is called injective if when $f(n) = f(m)$, then $n = m$. Suppose that $f$ is injective and $\frac{1}{f(n)}+\frac{1}{f(m)}=\frac{4}{f(n) + f(m)}$. Prove $m = n$