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If f (x) = cos ( log e x ) then ...

If f (x) `= cos ( log _e x ) ` then
` f(x) . f(y) - (1)/(2) [f(y/x ) + f (xy)]` has the value

A

1

B

`1/2`

C

`-2`

D

`0`

Text Solution

Verified by Experts

The correct Answer is:
D
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