1.求极限lim [(1-1/2^2)(1-1/3^2)...(1-1/n^2)] n趋向于无穷大.2.求∫∫ln(1+x^2+y^2)dxdy.其中圆周x^2+y^2=9及坐标轴所围成的在第一象限内的区域.

求极限lim 2/(3^n-1) 求极限 lim sin pi(n^2+1)^(1/2) 求极限 lim sin pi*(n^2+1)^(1/2) 求极限：lim{1+[1/(2n-1)]}^n 求极限：lim(1+1/x)(2-1/x²) 求极限：lim(1-2x)^(1/x), lim arctan[1/(x^2-1)] 求左右极限 求极限lim(1-2/x+3/x^2)^x 求极限lim【1-cosmx)/x^2】,x趋向0 求极限n~∞,lim(n+1)/2n 求极限：lim(x*sin(1/x))^2 lim x->0(sqrt(sin(1/x^2)) 求极限 求极限lim (e^x^2)/cosx-1 区域0 lim 1/2x x-->0 求极限 求lim(1-cos2x)/x^2极限,x→0 求极限：lim(1-x)tan Π/2 求极限lim(x-->0)x^2 sin(1/x), 求极限lim(x→0) (1-sinx)^(2/x)