Sum of fractions with restricted domain and range
Clash Royale CLAN TAG #URR8PPP up vote 0 down vote favorite Find all positive integers $m$ and $n$ so that for any $x$ and $y$ in the interval $[m, n]$, the value of $5/x + 7/y$ will also be in $ [m, n]$. I evaluated the inequalities into $(ym-5)(xm-7) < 35$ $(yn-5)(xn-7) > 35$ but can't really think of what to do next. inequality share | cite | improve this question edited Jul 31 at 13:04 asked Jul 31 at 10:14 SuperMage1 567 1 9 Are $x,y$ assumed to be positive? â Dr. Sonnhard Graubner Jul 31 at 10:16 yes they are000 â SuperMage1 Jul 31 at 10:17 You need $12nle n$, which is a bit difficult for non-zero numbers. Where did you get this question? â Macavity Jul 31 at 12:38 pmo.ph/wp-content/uploads/2014/08/16th-PMO-Area.pdf â SuperMage1 Jul 31 at 13:02 Its a...
