+0

# Let a, b, c, and d be positive integers. We know that... Find the maximum of...

0
21
0

Let $a$, $b$, $c$, and $d$ be positive integers. We know that

\begin{align*} a+b&=kc,\\ b+c&=kd,\\ c+d&=ka,\\ d+a&=kb. \end{align*}

Find the maximum of $\dfrac ab + \dfrac bc + \dfrac cd + \dfrac da.$

Nov 21, 2020