lim (1+1/2+1/4+…+1/2^n) / (1+1/3+1/9+…+1/3^n) (n→oo)lim (x^n)-1/x-1 (x→1)lim ((1/x+1)-(3/x^3 +1)) (x→-1)

lim(2an+4bn)=1 lim(3an-bn)=2 求lim(an+bn) lim(2an+4bn)=1 lim(3an-bn)=2 求lim(an+bn) lim(1/n+2/n+3/n+4/n+5/n+……+n/n)=lim(1/n)+lim(2/n)+……+lim(n/n)成立吗?（n趋近于无穷大）为什么不成立? X趋于0 Lim(xlnx)=Lim(lnx/(1/x))=Lim(1/x/(-1/x^2))=Lim(-x)=0Lim(lnx/(1/x))=Lim(1/x/(-1/x^2))其中这步使怎么转化的? 极限的简单运算lim an=3, lim bn=1/3, 求lim ((an-3bn)/2an) lim(1-1/n)^(n^2)=? lim(1-1/n^2)^n=? 极限：lim(x->2)1/(x-2) lim (e^x-sinx-1)/(arcsinx^2) lim 1/(x-2). 存在极限吗? Lim(-1/2)^n的极限是什么 求极限lim 2/(3^n-1) lim(1-(5/x))^x-2 lim(x+e^2x)^(1/sinx) lim(1+2/n)^m的极限? lim(x->0)(2xsinx)/(secx-1) lim(1-x)^(2/x) x->0 数学难题,求指教~~极限到底是什么玩意我还不懂.1.lim（x^2-2x+6）2.lim(x^2-4)/(x-2）3.lim(x^2-6x=8)/(x^-5x=4)4.lim[1/(1-x)-1/(1-x^3)5.lim(sin2x)/x^26.lim(sin5x)/x7.lim(tan3x)/(sin7x)8.lim[(1+x)/x]^2x例如这道例题~lim[(1/3)x+1]