Let f(x) be a function such that  `f(x+y)=f(x)+f(y) and f(x)=sin x g(x)" fora ll "x,y in R`.
Channel: Doubtnut
Date: 2020-05-17

Let f(x) be a function such that  `f(x+y)=f(x)+f(y) and f(x)=sin x g(x)" fora ll "x,y in R`. If g(x) is a continuous functions such that g(0)=k, then f'(x) is equal to