1/5x7+1/7x9+1/9x11+1/11x13+…+1/23x25
来源:学生作业帮 编辑:神马作文网作业帮 分类:数学作业 时间:2024/09/21 01:39:13
1/5x7+1/7x9+1/9x11+1/11x13+…+1/23x25
1/5x7+1/7x9+1/9x11+1/11x13+…+1/23x25
=1/2×(1/5-1/7+1/7-1/9+1/9-1/11+1/11-1/13+……+1/23-1/25)
=1/2×(1/5-1/25)
=1/2×4/25
=2/25
再问: 1/2哪里来的
再答: 1/5x7=1/2×(1/5-1/7) 1/7x9=1/2×(1/7-1/9) 1/9x11=1/2×(1/9-1/11) 1/11x13=1/2×(1/11-1/13) ………………………………… 1/23x25=1/2×(1/23-1/25)
=1/2×(1/5-1/7+1/7-1/9+1/9-1/11+1/11-1/13+……+1/23-1/25)
=1/2×(1/5-1/25)
=1/2×4/25
=2/25
再问: 1/2哪里来的
再答: 1/5x7=1/2×(1/5-1/7) 1/7x9=1/2×(1/7-1/9) 1/9x11=1/2×(1/9-1/11) 1/11x13=1/2×(1/11-1/13) ………………………………… 1/23x25=1/2×(1/23-1/25)
2x2/1x3+4x4/3x5+6x6/5x7+8x8/7x9+10x10/9x11+12x12/11x13 仔细看看
1/1x3+1/3x5+1/5x7+1/7x9+1/9x11=?
2/1x3+2/3X5+2/5x7=2/7x9+2/9x11
因式分解:X15+X14+X13+X12+X11+X10+X9+X8+X7+X6+X5+X4+X3+X2+X+1
已知1-1/3=2/1x3,计算1/1x3+1/3x5+1/5x7+1/7x9+1/9x11=
1、1x5分之1+5x9分之1+9x13分之1+……+97x101分之一是多少?
计算:1/1x3+1/3x5+1/5x7+1/7x9+……+1/2011x2013
1/1x4+1/4x7+1/7x10+1/10x13+1/13X16 简便
3/(1X4)+3/(4X7)+3/(7X10)+3/(10X13)+3/(13X16)
计算:1x4分之一+4x7分之一+7x10分之一+10x13分之一+13x16分之一
简算 6/5x13/1+9/5x13/2+18/5x13/6
1、5x6/1+6x7/1+7x8/1+8x9/1+9x10/1+……+19x20/1