lim (x→∞,y→∞) (x+y)/(x^2+y^2)=? A.1 B.0 C.2 Dlim (x→∞,y→∞) (x+y)/(x^2+y^2)=? A.1 B.0 C.2 D.-1

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, Lim(x+y)/(x2-xy+y2) (x,y)→(∞,∞)这个怎么算Lim(x,y)→(∞,∞) (x+y)/(x2-xy+y2) 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/(x-y) ⒈lim(x→a):(sinx-sina)/(x-a) a为常数⒉lim(x→∞):(1+k/x)^(-x) k为常数⒊lim(y→0):(1-5y)^(1/y) 证明下列极限不存在 lim(x→0,y→0) （X+Y)/(X-Y) 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) 一道数学题：lim(x,y)→(0,0)(x-y)/(x+y) lim(x,y)→(0,0) (1+xcosy)^(1/x)