1/1-1/3+1/5-1/7+1/9-1/11+……+1/(4n-3)-1/(4n-1)=?

lim(1/n^2+4/n^2+7/n^2+…+3n-1/n^2) 证明不等式：(1/n)^n+(2/n)^n+(3/n)^n+.+(n/n)^n 1除以（n+3）(n+4)+1除以(n+4)(n+5)+、、、1除以(n+10)(n+11)=? 用数学归纳法证明：1×2×3+2×3×4+…+n×(n+1)×(n+2)＝n(n+1)(n+2)(n+3)4(n∈N lim 9^n+4^n+2/5^n-3^2n-1 n趋于无穷大时 (1/(n^2 n 1 ) 2/(n^2 n 2) 3/(n^2 n 3) ……n/(n^2 n n)) 当N越于无穷大 Sn=n(n+2)(n+4)的分项等于1/6[n(n+2)(n+4)(n+5)-(n-1)n(n+2)(n+4)]吗? 化简：1/(n+1)(n+2)+1/(n+2)(n+3)+1/(n+3)(n+4) (n+1)(n+2)/1 +(n+2)(n+3)/1 +(n+3)(n+4)/1 证明：1+2C(n,1)+4C(n,2)+...+2^nC(n,n)=3^n .(n∈N+) 证明(1+2/n)^n>5-2/n（n属于N+,n>=3) (n+1)^n-(n-1)^n=?