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∫ x(cosx)^2 dx=?
人气:131 ℃ 时间:2020-03-25 14:23:51
解答
原式=∫x(1+cos2x)/2 dx
=1/2∫xdx+1/2∫xcos2x dx
=x²/4+1/4∫xcos2x d2x
=x²/4+1/4∫xdsin2x
=x²/4+1/4xsin2x-1/4∫sin2xdx
=x²/4+1/4xsin2x+1/8cos2x+C
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