求该函数的微分dy格式清晰.

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求该函数的微分dy格式清晰.
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求该函数的微分dy格式清晰.
求该函数的微分dy

格式清晰.

求该函数的微分dy格式清晰.
arctanx/y=1/2ln(x²+y²)
两边同时对x求导,得
1/[1+(x/y)²]*(y-xy')/y²=1/2*1/(x²+y²)*(2x+2yy')
(y-xy')/(x²+y²)=(x+yy')/(x²+y²)
y-xy'=x+yy'
(x+y)y'=y-x
y'=(y-x)/(x+y)
所以
dy=[(y-x)/(x+y)]*dx

两边对x求导得
1/[1+(x/y)^2]*(x/y)'=1/2*(x^2+y^2)'/(x^2+y^2)
y^2/(x^2+y^2)*(y-xy')/y^2=1/2*(2x+2yy')/(x^2+y^2)
y-xy'=1/2*(2x+2yy')=x+yy'
(x+y)y'=y-x
y'=(y-x)/(x+y)
dy=(y-x)/(x+y)*dx

两边对x求导得:
[1/(1+(x/y)^2)](y-xy')/y^2=(x+y')/(x^2+y^2)
(y-xy')/(x^2+y^2)=(x+y')/(x^2+y^2)
y-xy'=x+y'
y'=(y-x)/(1+x)
dy=[(y-x)/(1+x)]dx