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f(x+y) + f(x-y) =2f(x)f(y)

and f(0)=k

then find f(x)?

What should be approach followed to solve this question .

plz ans it soon

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# If f(x+y) + f(x-y) =2f(x)f(y) and f(0)=k then find f(x)?

**Physics Forums | Science Articles, Homework Help, Discussion**