lim(x→∞）1+2+3+…+n/(n+2)(n+4)=?

lim(x→∞）1+2+3+…+n/(n+2)(n+4)=? 求极限lim(x→∞)（1/n+2/n+3/n..+n/n） 求极限lim(-2)^n+3^n/(-2)^[n+1]+3^[n+1] (x→∞) 求极限,lim(x->0) (1-2sinx)^(3/x)lim(n->+∞) (n!-4^n) / (6+ln(n)+ 求lim n→∞ (1+2/n)^n+3 请问如何证明lim(n→∞)[n/(n2+n)+n/(n2+2n)+…+n/(n2+nn)]=1, 求极限：lim(n→∞)[（3n+1 ）/（3n+2）]^(n+1) 求极限 lim(n→∞)[根号(n^2+4n+5)-(n-1)] = 微积分lim(根号n^4+n+1)(3n+4)= （n->∞)lim{[(5x^2+1/3x-1)*sinx^-1]+( lim(n→∞)[1/(3n+1)+1/(3n+2)+~1/(3n+n)] 求极限lim [ 2^(n+1)+3^(n+1)]/2^n+3^n (n→∞) lim n →∞ (1^n+3^n+2^n)^1/n,求数列极限