Find second order derivative of `xcosx`

Explanation

Let` y=x \cdot \cos x`



`\Rightarrow \frac{d y}{d x}=\frac{d}{d x}(x \cdot \cos x)=\cos x \frac{d}{d x}(x)+x \frac{d}{d x}(\cos x)=\cos x \cdot 1+x(-\sin x)=\cos x-x \sin x `



`\therefore \frac{d^{2} y}{d x^{2}}=\frac{d}{d x}[\cos x-x \sin x]=\frac{d}{d x}(\cos x)-\frac{d}{d x}(x \sin x) `


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