求x^2cos^2x/2dx的不定积分

如题所述

第1个回答  2014-05-22
∫x^2[cos(x/2)]^2dx
=(1/2)∫x^2(1+cosx)dx
=(1/2)∫x^2dx+(1/2)∫x^2cosxdx
=(1/6)x^3+(1/2)∫x^2d(sinx)
=(1/6)x^3+(1/2)x^2sinx-(1/2)∫sinxd(x^2)
=(1/6)x^3+(1/2)x^2sinx-∫xsinxdx
=(1/6)x^3+(1/2)x^2sinx+∫xd(cosx)
=(1/6)x^3+(1/2)x^2sinx+xcosx-∫cosxdx
=(1/6)x^3+(1/2)x^2sinx+xcosx-sinx+C
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