1/1x4 + 1/4x7 + 1/7x10 +…+ 1/91x94=?
1/(1x4)+1/(4x7)+1/(7x10)+...+1/(91x94)
1X4/1+4X7/1+7X10/1+…+2005X2008/1=?
100x( 3/1x4 + 3/4x7 +3/7x10 +.3/97x100)=?注:1x4、4x7、7x10等均为分母
1/1x4+1/4x7+1/7x10+……+1/2005x2008
1/1x4+1/4x7+1/7x10+……+1/97x100
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
计算1/1x4+1/4x7+1/7x10+.+1/2002x2005+1/2005x2008
1/1x4+1/4x7+1/7x10+1/10x13+1/13X16 简便
计算1/1x4+1/4x7+1/7x10+***+1/2007x2010
1/1x4 +1/4x7+1/7x10+.+1/100x103 急用啊