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Kürschák Math Competition
1987 Kurschak Competition
1
1
Part of
1987 Kurschak Competition
Problems
(1)
a+b=cd, c+d=ab
Source: Kürschák 1987, problem 1
7/27/2014
Find all quadruples of positive integers
(
a
,
b
,
c
,
d
)
(a,b,c,d)
(
a
,
b
,
c
,
d
)
such that
a
+
b
=
c
d
a+b=cd
a
+
b
=
c
d
and
c
+
d
=
a
b
c+d=ab
c
+
d
=
ab
.
number theory unsolved
number theory