|1/3-1/4|+|1/4-1/5|+……+|1/20-1/19|怎么算?
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|1/3-1/4|+|1/4-1/5|+……+|1/20-1/19|怎么算?
急得很,不要用计算计算= =
急得很,不要用计算计算= =
![|1/3-1/4|+|1/4-1/5|+……+|1/20-1/19|怎么算?](/uploads/image/z/16627516-52-6.jpg?t=%7C1%2F3-1%2F4%7C%2B%7C1%2F4-1%2F5%7C%2B%E2%80%A6%E2%80%A6%2B%7C1%2F20-1%2F19%7C%E6%80%8E%E4%B9%88%E7%AE%97%3F)
前面的绝对值符号内都是正数,其绝对值等于它们本身,最后一个和前面不一样,绝对值等于它们的相反数,故:
原式=1/3-1/4+1/4-1/5+...+1/19-1/20
=1/3-1/20
=17/60
原式=1/3-1/4+1/4-1/5+...+1/19-1/20
=1/3-1/20
=17/60