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4/1*2*3+5/2*3*4+6/3*4*5+...+11/8*9*10

原是=4/2(1/1*2-1/2*3)+5/2(1/2*3-1/3*4)+6/2(1/3*4-1/4*5)+…… +11/2(1/8*9-1/9*10) 这是第一次裂项,将(1*2*3)分之4裂成4/2(1/1*2-1/2*3) (2*3*4)分之5裂成5/2(1/2*3-1/3*4)……依次类推 继续运算得 原是=1+1/2{1/2*3+1/3*4+……+1/8*9}-(11/2...

1/1*2*3+1/2*3*4+1/3*4*5+1/4*5*6+1/5*6*7+1/6*7*8+1/7*8*9+1/8*9*10+1/9*10*11 =(1/2)[(1/1*2)-(1/2*3)]+(1/2)[(1/2*3)-(1/3*4)]+(1/2)[(1/3*4)-(1/4*5)]+...+(1/2)[(1/9*10)-(1/10*11)] =(1/2)[(1/1*2)-(1/2*3)+(1/2*3)-(1/3*4)+(1/3*4)-(1/4*...

裂项法: 2*3/1*4+5*6/4*7+8*9/7*10+11*12/10*13+……+2012*2013/2011*2014 =1+2/1*4+1+2/4*7+1+2/7*10+1+2/10*13+……+1+2/2011*2014 =671+2/3*(1-1/4+1/4-1/7+1/7-1/10+1/10-1/13+……+1/2011-1/2014) =671+2/3*(1-1/2014) =671+2/3*2013/2014 =...

1³+2³+...+12³=(12×13/2)²=6084 公式:1³+2³+...+n³=[n(n+1)/2]²

1³+2³+3³+4³+++11³+……+n³=(n(n+1)/2)^2 你现在给的答案是66^2+12

非常留恋的这,睹貉蕴菠 挨

1/1*3=1/2(1/1-1/3),同理1/2*4=1/2(1/2-1/4)........1/9*11=1/2(1/9-1/11) 原式变为1/2(1/1-1/3)+1/2(1/2-1/4)+1/2(1/3-1/5)+........+1/2(1/9-1/11) =1/2(1/1+1/2-1/10-1/11) =1/2*144/110 =36/55

16*190 20*140 20*170 算出来;换乘公制;大概是这个数;有小数点就帮你省略了。1英寸=25.4mm

#include using namespace std; int main() { int i,j,n; cin>>n; int **a=new int*[n]; for(i=0;ib[j]; a[i]=b; } cout

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