2 1/2x5+4 1/5x8+6 1/8x11+...+100 1/149x150+102 1/152x155
1/2x5+1/5x8+1/8x11+.+1/32x35
裂项法1/2X5+1/5x8+1/8x11.1/2009x2012=?
求前n项和1.1/(2X5),1/(5X8),1/(8X11)...2.2^2/(1X3),4^2/(3X5),6^2/
2x5/1+5x8/1+8x11/1+.2006x2009/1+2009x2012/1 用裂项法计算
2x2/1x3+4x4/3x5+6x6/5x7+8x8/7x9+10x10/9x11+12x12/11x13 仔细看看
求数列1/2x5,1/5x8,1/8x11...,1/(3n-1)(3n+2)...的前n项和
1/2x5+1/5x8+1/8x11+…………+1/2003x2006+1/2006x2009 = 这是我儿子的小学作业
因式分解:X15+X14+X13+X12+X11+X10+X9+X8+X7+X6+X5+X4+X3+X2+X+1
2/1x3+2/3X5+2/5x7=2/7x9+2/9x11
1x2+2x3+3x4+4x5+……+10x11
1x5+2x5+3x5+4x5+5x5… 麻烦给我一个公式.
计算:1/1x2+1/2x3+1/3x4+1/4x5+1/5x6+1/6x7+1/7x8+1/8x9+1/9x10.