6.求下列各极限:-|||-(1) lim _((x,y)arrow (0,1))dfrac (1-xy)({x)^2+(y)^2} ;-|||-(3) lim _((x,y)arrow (0,0))dfrac (2-sqrt {xy+4)}(xy) :-|||-(5) lim _((x,y)arrow (2,0))dfrac (tan (xy))(y) =-|||-(2) lim _((x,y)arrow (1,0))dfrac (ln (x+{e)^y)}(sqrt {{x)^2+(y)^2}} :-|||-(4) lim _((x,y)arrow (0,0))dfrac (xy)(sqrt {2-{e)^xy}-1} :-|||-(6) lim _((x,y)arrow (0,0))dfrac (1-cos ({x)^2+(y)^2)}(({x)^2+(y)^2)(e)^(x^2{y)^2}}

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

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

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

求下列各极限:(1) lim_((x,y)to(0,1))(1-xy)/(x^2)+y^(2);(3) lim_((x,y)to(0,0))(2-sqrt(xy

lim _(xarrow y)dfrac (1-xy)({x)^2+(y)^2}-|||-bigcirc (3) lim 1-√(xy+1)-|||-y)→(0

计算lim _((x,y)arrow (0,0))dfrac (xy)(sqrt {xy+1)-1}=_____________计算_____________

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))(0,0)dfrac ({x)^2(y)^2}({x)^2+(y)^2} ;-||

7.试求下列极限:-|||-(1) lim _((x,y)arrow +infty )dfrac ({x)^2+(y)^2}({x)^4+(y)^4}-|||-

lim _((x, y)arrow (1,0)) (ln (1+xy))/(y) = ( ).A. -1B. 0C. 1D. 2