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Problem
Problem
Given the function
f
(
x
)
=
a
x
+
a
−
x
2
,
(
a
>
2
)
f(x) = \frac{a^x + a^{-x}}{2}, (a > 2)
f
(
x
)
=
2
a
x
+
a
−
x
,
(
a
>
2
)
. Then
f
(
x
+
y
)
+
f
(
x
−
y
)
=
f(x+y) + f(x-y) =
f
(
x
+
y
)
+
f
(
x
−
y
)
=
a.
2
f
(
x
)
f
(
y
)
2f(x)f(y)
2
f
(
x
)
f
(
y
)
b.
f
(
x
)
f
(
y
)
f(x)f(y)
f
(
x
)
f
(
y
)
c.
f
(
x
)
f
(
y
)
\frac{f(x)}{f(y)}
f
(
y
)
f
(
x
)
d. None of these
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