Find the second order derivative of the given functions.
x cos x
Ley y = x cos x
Differentiating twicely w.r.t. x, we get
dydx=ddx(x cos x)=x ddxcos x+cos x ddx(x)=(−x sin x)+cos x.1=−x sin x+cos x (Using product rule ddx(u. v)=udvdx+vdudx)and d2ydx2=ddx(−x sin x+cos x)=−ddx(x sin x)+ddx(cos x)=−{x cos x+sin x.1}−sin x=−x cos x−2 sin x (Using product rule])