求极限lim(x,y)→(0,0) 3xy/(xy+4)^1/2-2

求极限lim(x→0)x-sinx/x^3 lim(x→0y→1)(1+xe^y)^(2y+x/x)求极限 lim((x-y)/(x+y))求极限.(x,y)→(0,0) 求极限:lim(x→0)(tanx-sinx)/x^3 求lim(x→0)tanx/3x的极限 重赏求极限lim(x^2*|y|^3)/2/(x^4+y^2),x→0y→0 求极限lim (sinxy) / y x->a y->0 求极限：lim (x^2+y^2)^xy（x,y）lim (x^2+y^2)^xy x,y→0 这个极限是多少啊!怎么算? 求极限lim（x,y）→（0,0）3-根号下（xy+9）/2xy求极限 求lim x→0,y→0 xsin[1/(x+y)]的极限 求极限lim(x→0,y→0)xln(x^2+y^2)的值? 求极限lim Ln(1+x) /x > .< x→0 求极限 lim((x,y）→（0,0)) (x^2+y^2)sin1/xy 求极限:lim sin(x+y),(x,y)→(0,0)$(acontent) 求下列极限:lim[(x,y)→(0,0)][1/(x^2+y^2)] 求下列各极限 lim(x,y)→(0,1) (2-xy)/(x^2+2y) 求极限lim(x,y)→(0,0) 3xy/(xy+4)^1/2-2 求极限lim{x-0}(sinx)/X^3+3x