不定积分计算题,求个解答过程,谢谢
4个回答
2020-05-05
展开全部
解:设F(x)=cosx/x是f(x)的一个原函数,则f(x)=(-x*sinx-cosx)/x^2,
f(x/2)=[(-x/2)*sin(x/2)-cos(x/2)]/(x^2/4)
∫xf’(x/2)dx=2∫xdf(x/2)
=2xf(x/2)-2∫f(x/2)dx
=2xf(x/2)-4∫f(x/2)d(x/2)
=2xf(x/2)-4F(x/2)+C
=-8[(x/2)*sin(x/2)+cos(x/2)]/x-4cos(x/2)/(x/2)+C(C为常数)
=-8[(x/2)*sin(x/2)+cos(x/2)/x]/x-8cos(x/2)/x+C
我观察(随意看一下)各者答案似乎不同,我的答案还能化简一下,请自己继续化简一下,不求采纳,只愿你能明白!
f(x/2)=[(-x/2)*sin(x/2)-cos(x/2)]/(x^2/4)
∫xf’(x/2)dx=2∫xdf(x/2)
=2xf(x/2)-2∫f(x/2)dx
=2xf(x/2)-4∫f(x/2)d(x/2)
=2xf(x/2)-4F(x/2)+C
=-8[(x/2)*sin(x/2)+cos(x/2)]/x-4cos(x/2)/(x/2)+C(C为常数)
=-8[(x/2)*sin(x/2)+cos(x/2)/x]/x-8cos(x/2)/x+C
我观察(随意看一下)各者答案似乎不同,我的答案还能化简一下,请自己继续化简一下,不求采纳,只愿你能明白!
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