3n-(5n+2)化简

[3n(n+1)+n(n+1)(2n+1)]/6+n(n+2)化简 [3n(n+1)+n(n+1)(2n+1)]/6+n(n+2)化简 化简n分之n-1+n分之n-2+n分之n-3+.+n分之1 化简n分之n-1+n分之n-2+n分之n-3+.+n分之1 化简(n+1)(n+2)(n+3) 3n-(5n+2)化简 3(n-1)(n+3)-2(n-5)(n-2) 2^n*3^n*5^n+2/30^n 2^n*3^n*5^(n+1)/30^n 化简：1/(n+1)(n+2)+1/(n+2)(n+3)+1/(n+3)(n+4) n+(n+1)+(n+2)+(n+3)+(n+4)=5n+10这道题怎么解 m-{n+3n-[8m-(5n+2n)+3} 化简 化简16^n+2×4^n-1/8^2n×5^2n+4×2^n/5^2n+3×2^n+3 证明不等式：(1/n)^n+(2/n)^n+(3/n)^n+.+(n/n)^n 1/[n(n+1)]+1/[(n+1)(n+2)]+1/[(n+2)(n+3)]+1/[(n+3)(n+4)]+[(n+4)(n+5)}怎么算谢谢了, 1+(n+2)+(2n+3)+(3n+4)+(4n+5)+……((n-1)n+n)的答案 如果正整数n使得［n/2]+[n/3]+[n/4]+[n/5]+[n/6]=69,则n= 如果正整数n使得［n/2]+[n/3]+[n/4]+[n/5]+[n/6]=69,则n=