1/1x4+1/4x7+……+1/91x94=?

来源：学生作业帮编辑：作业帮分类：数学作业时间：2024/11/06 07:20:28

1/1x4=(1/3)*(1/1-1/4)
1/4*7=(1/3)(1/4-1/7)
..
1/91*94=(1/3)(1/91-1/94)
所以：
1/1x4+1/4x7+……+1/91x94
＝（1/3)*(1/1-1/4+1/4-1/7+..+1/91-1/94)
=(1/3)(1-1/94)
=31/94

1/(1x4)+1/(4x7)+1/(7x10)+...+1/(91x94) 1X4/1+4X7/1+7X10/1+…+2005X2008/1=? 1/1x4+1/4x7+1/7x10+……+1/2005x2008 1/1x4+1/4x7+1/7x10+……+1/97x100 100x( 3/1x4 + 3/4x7 +3/7x10 +.3/97x100)=?注：1x4、4x7、7x10等均为分母 1/1X4+1/4X7+1/7X10+...+1/100X103= 1/1X4+1/4X7+1/7X10+.+1/2002X2005=? 计算①1x2/1+2x3/1+3x4/1+```+19x20/1= ②1x4/1+4x7/1+7x10/1+```+91 x8+x7+x6+x5+x4+x3+x2+x+1因式分解 lim[1/(1x4)+1/(4x7)+1/(7x10)+...+1/(3n-2)x(3n+1)]=_____ 计算1/1x4+1/4x7+1/7x10+.+1/2002x2005+1/2005x2008 1/1x4+1/4x7+1/7x10+1/10x13+1/13X16 简便