1/1x3+1/3x5+...1/9x11用简便方法怎么计算?
1/1x3+1/3x5+1/5x7+1/7x9+1/9x11=?
2/1x3+2/3X5+2/5x7=2/7x9+2/9x11
已知1-1/3=2/1x3,计算1/1x3+1/3x5+1/5x7+1/7x9+1/9x11=
1x2+2x3+3x4+4x5+……+10x11
【分数】1/1x3+1/3x5+1/5x7+…+1/2009x2011要清楚过程的,乘用x代替,用简便方法计算
1/1x3+1/3x5+1/5x7+.+1/1997x1999 简便计算.
简便计算1/2+1/2x3+1/3x4+1/4x5+...+1/99x100
求前n项和1.1/(2X5),1/(5X8),1/(8X11)...2.2^2/(1X3),4^2/(3X5),6^2/
2x2/1x3+4x4/3x5+6x6/5x7+8x8/7x9+10x10/9x11+12x12/11x13 仔细看看
一道简便计算数学题1X2+2X3+3X4+4X5...+n(n+1)一1X2+2X3+3X4+4X5...+2013X2
因式分解:X15+X14+X13+X12+X11+X10+X9+X8+X7+X6+X5+X4+X3+X2+X+1
1/1x2+1/2x3+1/3x4+1/4x5...1/2001x2002 简便计算