2/2x4+2/4x6+2/6x8.2/8x10+2/10x2

1x2+2x4+3x6+4x8+5x10+.+20x40 怎么算? 1x2+2x4+3x6+4x8+5x10+.+20x40 简便计算 2x2/1x3+4x4/3x5+6x6/5x7+8x8/7x9+10x10/9x11+12x12/11x13 仔细看看 1x2+2x4+3x6+4x8 ------------------------------- 2x3+4x6+6x9+ 计算：1/1x2+1/2x3+1/3x4+1/4x5+1/5x6+1/6x7+1/7x8+1/8x9+1/9x10. （1x2+2x4+3x6+4x8）/（2x3+4x6+6x9+8x12) 2x3十4x6十6x9十8x12十10x15分之1x2十2x4十3x6十4x8十5x10. 2x4+4x6+6x8+.+98x100 1x2/1+2x3/1+3x4/1+.+2009x2010/1=? 2x4/1+4x6/1+6x8/1+.+2010x2 简算：2/2x4+2/4x6+2/6x8+……+2/98xl00 1/2x4+1/4x6+1/6x8+…+1/2010x2012 怎么算! 1/2x4+1/4x6+1/6x8+.+1/2010x2012