be a monic polynomial with integer coefficient. And suppose there exist 4 distinct integer 
such that 
.
such that 
such that ![\[f(2x+y) + f(x+f(2y)) = f(x)f(y) - xy\]](http://latex.artofproblemsolving.com/0/6/2/0623b7c328af6d088cfc5dd288afe3e17a94ff29.png)
for all reals 
and 
.
sastifying 
Y by Adventure10, Mango247, GeoKing
Let 
be an equilateral triangle. 
is the midpoint of segment 
and 
is the midpoint of segment 
. Let 
be the point outside such that the triangle 
is isosceles and right in . 
and 
are cut in 
. Prove that 
is the bisector of the angle 
.
be an equilateral triangle. 
is the midpoint of segment 
and 
is the midpoint of segment 
. Let 
be the point outside such that the triangle 
is isosceles and right in . 
and 
are cut in 
. Prove that 
is the bisector of the angle 
.
.
