问一道全微分选择题,如图第3题
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问一道全微分选择题,如图第3题
![](http://img.wesiedu.com/upload/d/e1/de1e7748cf96c06464a451f247e29e29.jpg)
![](http://img.wesiedu.com/upload/d/e1/de1e7748cf96c06464a451f247e29e29.jpg)
![问一道全微分选择题,如图第3题](/uploads/image/z/20252901-21-1.jpg?t=%E9%97%AE%E4%B8%80%E9%81%93%E5%85%A8%E5%BE%AE%E5%88%86%E9%80%89%E6%8B%A9%E9%A2%98%2C%E5%A6%82%E5%9B%BE%E7%AC%AC3%E9%A2%98)
∂z/∂y=y/(x+y)^2
z=∫ydy/(x+y)^2=ln(x+y)-y/(x+y)+g(x)
∂z/∂x=1/(x+y)+y/(x+y)^2+g'(x)
=(x+2y)/(x+y)^2+g'(x)
符合条件的是a=2
z=∫ydy/(x+y)^2=ln(x+y)-y/(x+y)+g(x)
∂z/∂x=1/(x+y)+y/(x+y)^2+g'(x)
=(x+2y)/(x+y)^2+g'(x)
符合条件的是a=2