(n+2)(10/11)^n+1 -(n+1)(10/11)^n怎么算?最好有解题全过程,
1除以(n+3)(n+4)+1除以(n+4)(n+5)+、、、1除以(n+10)(n+11)=?
2^n/n*(n+1)
证明不等式:(1/n)^n+(2/n)^n+(3/n)^n+.+(n/n)^n
lim[n/(n*n+1*1)+n/(n*n+2*2)+...+n/(n*n+n*n)],当x趋向无穷大时,怎么求极限,
1×2^2+2×3^2+3×4^2+...+n×(n+1)^2=n×(n+1)×(3n^2+11n+10)/12,用数学
n/2+90=1-n/10
{[(n+1)^(n+1)]/(n+1)!}*[n!/(n^n)]=?请高手赐教,最好写出步骤,
级数2/(n+2)(n+1)n 怎么求出答案
[3n(n+1)+n(n+1)(2n+1)]/6+n(n+2)化简
化简(n+1)(n+2)(n+3)
n(n+1)(n+2)数列求和
n(n+1)(n+2)等于多少?