∞Σ n^(-2)n=1

∞Σ n^(-2)n=1 ∞ Σ 3n^n/(1+n)^n 判定收敛性 n=1∞ -------------------------------------------------------------------------------------------------------------Σ 3n^n/(1+n)^n ---------------------------------------------------------------------------------- ∞ Σ 3n^n/(1+n)^n 判定收敛性 n=1, ∑(∞,n=1)(n^2-2n+3)/(n^4+n^2-6) 设f(n)=1+2+3+.n,则(n-->+∞)limf(n)/[f(n)]= 判断敛散性：∑(n=1~∞) (4^n*n!*n!)/(2n)! Σ ∞ n=1 ( n(n+1)^4)^-1 f(x)=e^x-x 求证(1/n)^n+(2/n)^n+...+(n/n)^n lim n->∞{2/((1+ 1/n )^n)}=? lim n--∞ (1+2/n)^n=?如题 当n为正偶数,求证n/(n-1)+n(n-2)/(n-1)(n-3)+...+n(n-2).2/(n-1)(n-3)...1=n 大一微积分解答：lim(n→+∞)（2^n+4^n+6^n+8^n）^1/n=? lim(n→∞) (1/n)[sin(π/n)+sin(2π/n)+…+sin(nπ/n)]=? ∞∑ n=1 [(2n-1)/(3^n)]*[x^(2n-2)] ∞∑ n=1 [((-1)^n)/(2n-1)*(x^(2n) 2n*1/2^n=n/2^(n-1)? 阶乘(2n-1)!=（2n)!/(2^n*n! 为什么n!/(2!(n-2)!)=n(n-1)/2! 高数题：n趋近于0,lim｛1/（n^2+n+1)+2/(n^2+n+2)+3/(n^2+n+3)+.+n/(n^2+n+n)｝=?