(x→∞,y→∞)lim(x^2+y^2)÷(arctanx+(x-y)^2)求极限

lim(x→∞,y→∞) x+y/x^2-xy+y^2 求极限lim(x→+∞,y→+∞) (X+Y)/(X^2-Y^2) lim(x→∞,y→∞) x+y/x^2-xy+y^2 lim(x→+∞,y→0) (1+1/x)^(x^2/(x+y)) 1.lim(2x-sinx)/(2x+sinx) (x→0)2.lim(sinsinx)/x (x→0)3.lim 4/y (y→∞) 求极限lim(x,y)→(+∞,+∞) [(xy)/(x^2+y^2)]^xy.求极限lim(x,y)→(+∞,+∞) [(xy)/(x^2+y^2)]^xy, 求极限lim(x,y)→(+∞,+∞) (xy/(x^2+y^2))^x^2 (x→∞,y→∞)lim(x^2+y^2)÷(arctanx+(x-y)^2)求极限 求极限 lim(x→ +∞,y→ +∞) (x^2+y^2)/(x^4+y^4)? 多元函数极限求解lim(x→∞,y→∞)((x+y)/(x^2+xy+y^2))=? lim(x→0y→1)(1+xe^y)^(2y+x/x)求极限 lim(x,y)->(∞,a)(1-1/x)^（x^2/x+y） Lim(x+y)/(x2-xy+y2) (x,y)→(∞,∞)这个怎么算Lim(x,y)→(∞,∞) (x+y)/(x2-xy+y2) f(x,y)=3xy/x^2+y^2 lim(x→0)(lim(y→0)f(x,y)) 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? 证明下列极限不存在(1) Lim x+y/x-y (2)lim x²y²/ x²y²+(x-y)²(x,y)→(0,0) (x,y)→(0,0) 求极限lim(x→0,y→0)xln(x^2+y^2)的值? 试证明极限 lim(x^2*y^2)/(x^2*y^2+(x-y)^2)不存在还有一题 计算二重极限lim(x^2+y^2)sin(1/(x^2+y^2))x→0，y→0