|1/3-1/4|+|1/4-1/5|+.+|1/19-1/20|=
来源:学生作业帮助网 编辑:作业帮 时间:2024/07/28 06:47:31
![|1/3-1/4|+|1/4-1/5|+.+|1/19-1/20|=](/uploads/image/z/26651-11-1.jpg?t=%7C1%2F3-1%2F4%7C%2B%7C1%2F4-1%2F5%7C%2B.%2B%7C1%2F19-1%2F20%7C%3D)
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|1/3-1/4|+|1/4-1/5|+.+|1/19-1/20|=
|1/3-1/4|+|1/4-1/5|+.+|1/19-1/20|=
|1/3-1/4|+|1/4-1/5|+.+|1/19-1/20|=
|1/3-1/4|+|1/4-1/5|+.+|1/19-1/20|
=(1/3-1/4)+(1/4-1/5)+(1/5-1/6)+...+(1/19-1/20)
=1/3-1/4+1/4-1/5+1/5-1/6+...1/19-1/20
=1/3-1/20
=17/60
17/60
其实绝对值符号是骗人的,都是大的减小的,所以绝对值符号可以不要,最后就变成了1/3-1/20,这有什么难呢,就等于17/60
17/60
17/60
原式=1/3-1/4+1/4-1/5+...-1/19+1/19-1/20
=1/3-1/20
=17/60