计算 1/1*5+1/5*9+1/9*13.+1/2009*2013

来源:学生作业帮助网 编辑:作业帮 时间:2024/05/08 15:10:16
计算 1/1*5+1/5*9+1/9*13.+1/2009*2013

计算 1/1*5+1/5*9+1/9*13.+1/2009*2013
计算 1/1*5+1/5*9+1/9*13.+1/2009*2013

计算 1/1*5+1/5*9+1/9*13.+1/2009*2013

1/1*5+1/5*9+1/9*13......+1/2009*2013
=1/4*(1-1/5+1/5-1/9+1/9-1/13+......+1/2009-1/2013)
=1/4*(1-1/2013)
=503/2013

1/1*5+1/5*9+1/9*13......+1/2009*2013
=1/4×(1-1/5+1/5-1/9+1/9-1/13+...+1/2009-1/2013)
=1/4×(1-1/2013)
=1/4×2012/2013
=503/2013

1/1*5=(1-1/5)*1/4,
1/5*9=(1/5-1/9)*1/4
所以原式
=(1-1/5)*1/4+(1/5-1/9)*1/4+(1/9-1/13)*1/4+…+(1/2009-1/2013)*1/4
=(1-1/2013)*1/4

1/1*5+1/5*9+1/9*13......+1/2009*2013
=1/4(1-1/5)+1/4(1/5-1/9)+....+1/4(1/2009-1/2013)
=1/4(1-1/2013)(中间约去)
=503/2013