Question

高数题 计算积分∫x²cosxdx

Answer 1

∫x^2cosxdx
=∫x^2d(sinx)
=x^2sinx-∫sinxd(x^2)
=x^2sinx-2∫xsinxdx
=x^2sinx+2∫xd(cosx)
=x^2sinx+2xcosx-2∫cosxdx
=x^2sinx+2xcosx-2sinx+C
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