Are there positive integers $m,n$ such that there exist at least $2012$ positive integers $x$ such that both $m-x^2$ and $n-x^2$ are perfect squares? David Yang.
Problem
Source: ELMO Shortlist 2012, N9
Tags: number theory proposed, number theory
04.02.2013 22:38
OK... if anyone is interested, see the original thread here. Hence an excellent ELSMO problem.
13.10.2014 01:50
Does anyone have a full solution?
24.05.2016 22:18
Can someone post a solution to this interesting problem? Thanks!
25.05.2016 00:51
This is basically asking if there's 2 positive integers m and n such that each can be written as the sum of 2 positive squares in 2012 different ways, which is clearly true. Two such examples are found by raising 5 or 13 to any sufficiently large number
25.05.2016 01:12
@above not quite. The question is asking whether there exist two positive integers $m$ and $n$ such that they can be written as a sum of 2 positive squares 2012 ways each such that there is a matching of the pairs where pairs that are connected share an element.
24.08.2017 18:51
MathPanda1 wrote: Does anyone have a full solution?
03.11.2017 03:30
MathPanda1 wrote: Does anyone have a full solution?
20.05.2018 16:17
Seems like a hard problem -- No full solutions?
26.12.2018 23:49
Bumb. Can't believe this has not been answered yet. (@MathFiFi I don't actually. The "can't believe" thing was not meant to be intimidating. It is a surprise that the post has over 2000 views and no one has posted a solution yet )
27.12.2018 00:00
Hamel wrote: Bumb. Can't believe this has not been answered yet. do you know the answer? if so can you post it?
01.01.2019 12:07
Can the creator at least shed some light upon this?
01.01.2019 17:34
i think $m,n$ should be distince,otherwise we can pick $m=n$ and we need to find an integer $m$ such that $m$ can be written as sum of 2 squares in 2012 ways, which can easily proved by the identy $(a^2+b^2)(c^2+d^2)=(ac+bd)^2+(ad-bc)^2$
01.01.2019 17:40
Hamel wrote: Can the creator at least shed some light upon this? common sense much? lol 2012, y'think hes active on aops??
10.01.2019 22:00
Math-Ninja wrote: Hamel wrote: Can the creator at least shed some light upon this? common sense much? lol 2012, y'think hes active on aops?? im assuming David Yang is the creator, not the OP
11.01.2019 00:26
There was already a full solution posted in #2, you just have to follow the link. Here it is again.