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Problem
Problem
Given
f
(
x
)
f(x)
f
(
x
)
is a polynomial function of
x
x
x
, satisfying
f
(
x
)
⋅
f
(
y
)
=
f
(
x
)
+
f
(
y
)
+
f
(
x
y
)
−
2
f(x) \cdot f(y) = f(x) + f(y) + f(xy) - 2
f
(
x
)
⋅
f
(
y
)
=
f
(
x
)
+
f
(
y
)
+
f
(
x
y
)
−
2
and that
f
(
2
)
=
5
f(2) = 5
f
(
2
)
=
5
. Then
f
(
3
)
f(3)
f
(
3
)
is equal to
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