Question:
if f(x)=x cos x, find f"(x), or d2ydx2
Physics Calculus Differentiation
Solution:
Using the Product Rule, we have f'(x)=xddx(cos x)+cos xddx(x)=-xsinx+cosx To find f"(x) we differentiate f'(x): f"(x)=ddx(-x sin x+cos x)=-xddx(sin x)+sin x ddx(-x)+ddx(cos x) =-x cos x-sin x-sin x = -x cos x-2 sin x
my problem is :
I didn't understand how to solve this question
Given f(x) = g(X) . h (x) and f′(x)=g′(x)h(x) + g(x)h′(x) find f'(x) where f(x) = x sin x.
If
A. cos x + x sin x
B. x sin x
C. x cos x
D. sin x + x cos x