1/1x5+1/5x9+1/9x13+1/13x17+1/17x21=?如何简便运算?

来源：学生作业帮编辑：拍题作业网作业帮分类：数学作业时间：2024/05/01 22:40:11

1/1x5+1/5x9+1/9x13+1/13x17+1/17x21
=1/4x(1-1/5)+1/4x(1/5-1/9)+1/4x(1/9-1/13)+1/4x(1/13-1/17)+1/4x(1/17-1/21)
=1/4x(1-1/5+1/5-1/9+1/9-1/13+1/13-1/17+1/17-1/21)
=1/4x(1-1/21)
=5/21

1、1x5分之1+5x9分之1+9x13分之1+……+97x101分之一是多少? 2x2/1x3+4x4/3x5+6x6/5x7+8x8/7x9+10x10/9x11+12x12/11x13 仔细看看因式分解:X15+X14+X13+X12+X11+X10+X9+X8+X7+X6+X5+X4+X3+X2+X+1 1/1X3+1/3X5+1/5X7...1/17X19+1/19X21= 1/1x3+1/3x5+1/5x7+1/7x9+1/9x11=? 2/1x3+2/3X5+2/5x7=2/7x9+2/9x11 2/1X3+2/3X5+2/5x7+.+2/19x21 简算 6/5x13/1+9/5x13/2+18/5x13/6 (2X2)/1X3+(4X4)/(3X5)+(6X6)/(5X7)+...+(20X20)/(19X21)==? 奥数简便运算41.2X8.1+11X9.25+53.7X1.9 (39/1+35/2)x13+35/9怎样简便算简便计算：（2/9+1/13)x9+4/13