用对数求导法求导:y=[x*(x^2+1)/(x-1)^2]^1/3

问题描述:

用对数求导法求导:y=[x*(x^2+1)/(x-1)^2]^1/3
1个回答 分类:数学 2014-12-11

问题解答:

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等式两边取对数有:lny=1/3ln[x*(x^2+1)/(x-1)^2]
化简得3lny=lnx+ln(x^2+1)-2ln|x-1|
两边求导3y'/y=1/x+2x/(x^2+1)-2/(x-1)
y'=1/3*y[1/x+2x/(x^2+1)-2/(x-1)]
=1/3*[1/x+2x/(x^2+1)-2/(x-1)]*[x*(x^2+1)/(x-1)^2]^1/3
 
 
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