lim√[(3n^2)+1]/(7n+1)=?

lim[(n+3)/(n+1))]^(n-2) 【n无穷大】 lim(1/n^2+4/n^2+7/n^2+…+3n-1/n^2) lim 1+4+7+...+(3n-2)/n(n+1)=______ 求极限：lim(x→无穷)(2^n-7^n)/(2^n+7^n-1)=? lim n->无穷大(2^n-1)/(3^n+1) lim根号n^2+n+1/3n-2 lim(3^2n+5^n)/(1+9^n) 求lim n→∞ (1+2/n)^n+3 求1.lim(3n-(3n^2+2n)/(n-1)) 2.lim(8+1/(n+1)) 3.lim根号n(根号(n+1) lim n趋向无穷大(3^n+2^n)/(3^（n+1）-2^（n+1）)=? lim(n→∞)[1/(3n+1)+1/(3n+2)+~1/(3n+n)] lim n趋于无穷大(1/n^2+3/n^2+.+2n-1/n^2