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微积分,分部积分的题
1个回答
2015-07-11 · 知道合伙人教育行家
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设F(u)=∫(0→u)f(x)dx
则 F'(u)=f(u)
右边=∫(0→x)F(u)du
=uF(u) |(0→x)
-∫(0→x)uF'(u)du
=x∫(0→x)f(u)du
-∫(0→x)uf(u)du
=∫(0→x)xf(u)du
-∫(0→x)uf(u)du
=∫(0→x)(x-u)f(u)du
=左边
则 F'(u)=f(u)
右边=∫(0→x)F(u)du
=uF(u) |(0→x)
-∫(0→x)uF'(u)du
=x∫(0→x)f(u)du
-∫(0→x)uf(u)du
=∫(0→x)xf(u)du
-∫(0→x)uf(u)du
=∫(0→x)(x-u)f(u)du
=左边
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