lim(x→-∞)x-2/(x+1)^2 (分子分母同除以x平方)
=lim(x→-∞)(1/x-2/x²)/(1+1/x)^2
=0/1
=0lim(x→-∞)x-2/(x+1)^2 (分子分母同除以x平方)这里能详解吗？能列一条式子出来吗？（x-2)/x²=1/x -2/x²(x+1)^2 /x^2=(1+1/x)^2