3.lim_((x,y)to(0,0))(x^2)/(x^2)+y^(2)的结果是

极限 lim_((x,y)to (0,0)) (x^2 y)/(x^4 + y^2) = ( )A. 等于 0；B. 不存在；C. 等于 $\frac{1}{2

极限 lim_((x,y)to (0,0)) (x^2y)/(x^4 + y^2) ().A. 等于0B. 不存在C. 等于2D. 存在但不等于0

试求下列极限(包括非正常极限):-|||-(1) lim _((x,y))(dfrac ({x)^2(y)^2}({x)^2+(y)^2}-|||-(2) li

试应用 -8 定义证明:-|||-lim _(x,y))(0,0)dfrac ({x)^2y}({x)^2+(y)^2}=0.

2【单选题】设f(x,y)=}(x^2+y^2)sin(1)/(sqrt(x^2)+y^(2)),(x,y)neq(0,0)0,(x,y)=(0,0)f(x,y

1.试求下列极限(包括非正常极限):-|||-(1) lim _((x,y))(0,0)dfrac ({x)^2(y)^2}({x)^2+(y)^2} ;-||

4.证明:(1) lim _((x,y)arrow (0,0))dfrac (x+y)(x-y) 不存在;(2)-|||-lim _((x,y)arrow (0

1.试求下列极限(包括非正常极限):-|||-(1) lim _((x,y)arrow (0,0))dfrac ({x)^2(y)^2}({x)^2+(y)^2

8.函数f(x,y)=}(xy)/(x^2)+y^(2),x^2+y^2neq0,0,x^2+y^2=0,在(0,0)点（）A. 连续，偏导函数都存在B. 不连

6.求下列各极限:-|||-(1) lim _((x,y)arrow (0,1))dfrac (1-xy)({x)^2+(y)^2} :-|||-(3) lim