1+3+5+7+9+.+(2n-1)+(2n+1)+(2n+3)=
证明不等式:(1/n)^n+(2/n)^n+(3/n)^n+.+(n/n)^n
证明(1+2/n)^n>5-2/n(n属于N+,n>=3)
1 + (n + 1) + n*(n + 1) + n*n + (n + 1) + 1 = 2n^2 + 3n + 3
1\n(n+3)+1\(n+3)(n+6)+1\(n+6)(n+9)=1\2 n+18 n为正整数,求n的值
lim 9^n+4^n+2/5^n-3^2n-1 n趋于无穷大时
[3n(n+1)+n(n+1)(2n+1)]/6+n(n+2)化简
化简(n+1)(n+2)(n+3)
lim(3^2n+5^n)/(1+9^n)
M=(N-1)×1+(N-2)×2+(N-3)×4+(N-4)×8+(N-5)×16+(N-6)×32+(N-7)×64
证明:1+2C(n,1)+4C(n,2)+...+2^nC(n,n)=3^n .(n∈N+)
已知888个连续正整数之和:n+(n+1)+(n+2)+(n+3)+(n+4)+(n+5)+(n+6)+(n+7)+··
计算:n(n+1)(n+2)(n+3)+1