Đặt: \(\left\{\begin{array}{l} {u=x^{2} } \\ {{\rm d}v=\cos x{\rm d}x} \end{array}\right. \Rightarrow \left\{\begin{array}{l} {{\rm d}u=2x{\rm d}x} \\ {v=\sin x} \end{array}\right. \Rightarrow \int x^{2} \cos x{\rm d}x =x^{2} \sin x-2\int x\sin x{\rm d}x\)
Đặt \(\left\{\begin{array}{l} {u=x} \\ {{\rm d}v=\sin x{\rm d}x} \end{array}\right. \Rightarrow \left\{\begin{array}{l} {{\rm d}u={\rm d}x} \\ {v=-{\rm co}sx} \end{array}\right. \Rightarrow \int x\sin x{\rm d}x =-x{\rm co}sx+\int \cos x{\rm d}x =-x{\rm co}sx+\sin x+C_{1}\)
Vậy \(\int x^{2} \cos x{\rm d}x =x^{2} \sin x+2x{\rm cos}x-2\sin x+C.\)