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Putnam
1968 Putnam
A2
A2
Part of
1968 Putnam
Problems
(1)
Putnam 1968 A2
Source: Putnam 1968
2/19/2022
Given integers
a
,
b
,
c
,
d
,
m
,
n
a,b,c,d,m,n
a
,
b
,
c
,
d
,
m
,
n
such that
a
d
−
b
c
≠
0
ad-bc\ne 0
a
d
−
b
c
=
0
and any real
ε
>
0
\varepsilon >0
ε
>
0
, show that one can find rational numbers
x
,
y
x,y
x
,
y
such that
0
<
∣
a
x
+
b
y
−
m
∣
<
ε
0<|ax+by-m|<\varepsilon
0
<
∣
a
x
+
b
y
−
m
∣
<
ε
and
0
<
∣
c
x
+
d
y
−
n
∣
<
ε
0<|cx+dy-n|<\varepsilon
0
<
∣
c
x
+
d
y
−
n
∣
<
ε
.
Putnam
approximation