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Korea Junior Mathematics Olympiad
2011 Korea Junior Math Olympiad
3
3
Part of
2011 Korea Junior Math Olympiad
Problems
(1)
x,y coprime, x + 3y^2 perfect square, x^2 + 9y^4 not a perfect square
Source: KJMO 2011 p3
5/4/2019
Let
x
,
y
x, y
x
,
y
be positive integers such that
g
c
d
(
x
,
y
)
=
1
gcd(x, y) = 1
g
c
d
(
x
,
y
)
=
1
and
x
+
3
y
2
x + 3y^2
x
+
3
y
2
is a perfect square. Prove that
x
2
+
9
y
4
x^2 + 9y^4
x
2
+
9
y
4
can't be a perfect square.
number theory
coprime
Perfect Square