分数裂项,请给出详解!谢谢!
来源:学生作业帮 编辑:大师作文网作业帮 分类:数学作业 时间:2024/11/12 12:16:57
分数裂项,请给出详解!谢谢!
计算:4/3+16/15+36/35+64/63+100/99+144/143+196/195+256/255=----------
计算:4/3+16/15+36/35+64/63+100/99+144/143+196/195+256/255=----------
这道题就是要题中的各个分数拆分成下面的减法算式,达到正负抵消,从而使计算简便.这样的方法就是拆分法,又叫“裂项法”.
4/3=1+1/3=1+(1-1/3)×1/2
16/15=1+1/15=1+(1/3-1/5)×1/2
36/35=1+1/35=1+(1/5-1/7)×1/2
64/63=1+1/63=1+(1/7-1/9)×1/2
100/99=1+1/99=1+(1/9-1/11)×1/2
144/143=1+1/143=1+(1/11-1/13)×1/2
196/195=1+1/195=1+(1/13-1/15)×1/2
256/255=1+1/255=1+(1/15-1/17)×1/2
4/3+16/15+36/35+64/63+100/99+144/143+196/195+256/255
=1+1/3+1+1/15+1+1/35+1+1/63+1+1/99+1+1/143+1+1/195+1+1/255
=1×8+(1/3+1/15+1/35+1/63+1/99+1/143+1/195+1/255)
=8+(1-1/3+1/3-1/5+1/5-1/7+1/7-1/9+1/9-1/11+1/13-1/15+1/15-1/17)×1/2
=8(1-1/17)×1/2
=8+16/17×1/2
=8+8/17
=8又8/17
4/3=1+1/3=1+(1-1/3)×1/2
16/15=1+1/15=1+(1/3-1/5)×1/2
36/35=1+1/35=1+(1/5-1/7)×1/2
64/63=1+1/63=1+(1/7-1/9)×1/2
100/99=1+1/99=1+(1/9-1/11)×1/2
144/143=1+1/143=1+(1/11-1/13)×1/2
196/195=1+1/195=1+(1/13-1/15)×1/2
256/255=1+1/255=1+(1/15-1/17)×1/2
4/3+16/15+36/35+64/63+100/99+144/143+196/195+256/255
=1+1/3+1+1/15+1+1/35+1+1/63+1+1/99+1+1/143+1+1/195+1+1/255
=1×8+(1/3+1/15+1/35+1/63+1/99+1/143+1/195+1/255)
=8+(1-1/3+1/3-1/5+1/5-1/7+1/7-1/9+1/9-1/11+1/13-1/15+1/15-1/17)×1/2
=8(1-1/17)×1/2
=8+16/17×1/2
=8+8/17
=8又8/17