x,y趋近于0,lim(xy/(x+y))=lim(1/(1/x+1/y))=0错哪里了?我知道要令y=x,y=x^2-x,但是请问lim(xy/(x+y))=lim(1/(1/x+1/y))=0的做法错哪里了?
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![x,y趋近于0,lim(xy/(x+y))=lim(1/(1/x+1/y))=0错哪里了?我知道要令y=x,y=x^2-x,但是请问lim(xy/(x+y))=lim(1/(1/x+1/y))=0的做法错哪里了?](/uploads/image/z/6889589-53-9.jpg?t=x%2Cy%E8%B6%8B%E8%BF%91%E4%BA%8E0%2Clim%28xy%2F%28x%2By%29%29%3Dlim%281%2F%281%2Fx%2B1%2Fy%29%29%3D0%E9%94%99%E5%93%AA%E9%87%8C%E4%BA%86%3F%E6%88%91%E7%9F%A5%E9%81%93%E8%A6%81%E4%BB%A4y%3Dx%2Cy%3Dx%5E2-x%2C%E4%BD%86%E6%98%AF%E8%AF%B7%E9%97%AElim%28xy%2F%28x%2By%29%29%3Dlim%281%2F%281%2Fx%2B1%2Fy%29%29%3D0%E7%9A%84%E5%81%9A%E6%B3%95%E9%94%99%E5%93%AA%E9%87%8C%E4%BA%86%3F)
x,y趋近于0,lim(xy/(x+y))=lim(1/(1/x+1/y))=0错哪里了?我知道要令y=x,y=x^2-x,但是请问lim(xy/(x+y))=lim(1/(1/x+1/y))=0的做法错哪里了?
x,y趋近于0,lim(xy/(x+y))=lim(1/(1/x+1/y))=0错哪里了?
我知道要令y=x,y=x^2-x,但是请问lim(xy/(x+y))=lim(1/(1/x+1/y))=0的做法错哪里了?
x,y趋近于0,lim(xy/(x+y))=lim(1/(1/x+1/y))=0错哪里了?我知道要令y=x,y=x^2-x,但是请问lim(xy/(x+y))=lim(1/(1/x+1/y))=0的做法错哪里了?
求极限时,如果代入后分母是零,肯定是不能直接代入的.
lim(x,y→0),1/x;1/y,不能直接把0代入得出无穷大,这一步是错的.