求下列极限 1.lim x→0y→2 sin(xy)/x 2.lim x→0y→0 (2-√（xy+4）)/xy

题目

求下列极限 1.lim x→0y→2 sin(xy)/x 2.lim x→0y→0 (2-√（xy+4）)/xy
3.lim x→0y→0(x^2y)/(x^3-y^3) 4.limx→0y→1 xy*sin(1/(x^2+y^2))

答案