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19
I 19
I 19
Source:
May 25, 2007
floor function
function
trigonometry
Problem Statement
Let
a
,
b
,
c
a, b, c
a
,
b
,
c
, and
d
d
d
be real numbers. Suppose that
⌊
n
a
⌋
+
⌊
n
b
⌋
=
⌊
n
c
⌋
+
⌊
n
d
⌋
\lfloor na\rfloor +\lfloor nb\rfloor =\lfloor nc\rfloor +\lfloor nd\rfloor
⌊
na
⌋
+
⌊
nb
⌋
=
⌊
n
c
⌋
+
⌊
n
d
⌋
for all positive integers
n
n
n
. Show that at least one of
a
+
b
a+b
a
+
b
,
a
−
c
a-c
a
−
c
,
a
−
d
a-d
a
−
d
is an integer.
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