5^2·3^2n+1·2^n-3^n·6^n+2能被13整除.

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)+···+(n+887)是一个平方数 求n -(a^2n)^5 n·n^4-n^2·n^3上课没咋听懂n·n^4-n^2·n^3 证明不等式：(1/n)^n+(2/n)^n+(3/n)^n+.+(n/n)^n 若n等于-1,则n-2n+3n-4n+5n-6n+······+99n-100n的值为______ [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 limn趋近于无穷2·5^n+3^n/5^n+1+2^n+1 1*n+2(n-1)+3(n-2)+······+n*1=1/6*n(n+1)(n+2) Sn=0·1/n+(1/n)^2·1/n+...+(i/n)^2+...+(n-1/n)^2·1/n怎么算出等于(n-1)n(2n-1)/6n^3=1/n^3[1^2+2^2+...i^2+...+(n-1)^2]=(n-1)·n·(2n-1)/6n^3=1/3-(1/2n-1/6n^2)这里面的第二步. 3(n-1)(n+3)-2(n-5)(n-2) 5^2·3^2n+1·2^n-3^n·6^n+2能被13整除. 2^n*3^n*5^(n+1)/30^n 六个共面共点力大小分别是1N,2N,2N,3N,4N,5N,和6N,相互之间的夹角均为60·,则他们合力的大小为多少N!不然小弟我看不懂!快, 求证：N=(5^2)*(3^2n+1)*(2^n)-(3^n)*(6^n+2) n+(n+1)+(n+2)+(n+3)+(n+4)=5n+10这道题怎么解 求级数1/[3^n+(-2)^ n]·x^n/n的收敛域 试说明:5^2·3^2n+1·2^n-6^n·3^n·6^n能被13整除. 下列几组力中,合力不可能等于0的是 A.3N 4N 6N B.1N 2N 4N C.2N 4N 6N D.5N 5N 1N