FunctionHard
Question
If f(x) = cos(ln x), then f(x) f(y) -
has the value
has the valueOptions
A.-1
B.1/2
C.-2
D.None of these
Solution
f(x) = cos (ln x)
f(x) . f(y) = cos(ln x) . cos (ln y)
f (x/y) + f(xy) = cos (ln x - lny) + cos (ln x + ln y)
∴ f(x) . f(y) -
= cos (ln x) cos (ln y) - 
[2 cos(lnx) cos (ln y) = 0
f(x) . f(y) = cos(ln x) . cos (ln y)
f (x/y) + f(xy) = cos (ln x - lny) + cos (ln x + ln y)
∴ f(x) . f(y) -
= cos (ln x) cos (ln y) - [2 cos(lnx) cos (ln y) = 0Create a free account to view solution
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