A) \[\cos x\]
B) \[f(\log x)\]
C) \[\cos (\log x)\]
D) \[\frac{\cos (\log x)}{x}\]
E) \[\frac{\cos (\log x)}{2x}\]
Correct Answer: D
Solution :
Given, \[f(x+y)=2f(x)f(y)\] \[\therefore \] \[f(\log x)=\sin \log x\] On differentiating w.r.t.\[x,\]we get \[f(\log x)=\cos (\log x).\frac{1}{x}\]You need to login to perform this action.
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