|1/2-1|+|1/3-1/2|+|1/4-1/3|+······+|1/2008-1/2007|
怎么算?帮帮忙!
|1/2-1|+|1/3-1/2|+|1/4-1/3|+······+|1/2008-1/2007|
怎么算?帮帮忙!
原式=(1-1/2)+(1/2-1/3)+...+(1/2007-1/2008)
=1-1/2+1/2-1/3+...+1/2007-1/2008
=1-1/2008
=2007/2008
解:绝对值里面的数的结果均小于零。所以去绝对值,前面应加负号
所以
原式=(1-1/2)+(1/2-1/3)+............+(1/2007-1/2008)
=1-1/2008
=2007/2008
把绝对值去掉 因为每个式子都大于0 所以去掉绝对值不变号
原式=(1-1/2)+(1/2-1/3)+...+(1/2007-1/2008)
=1-1/2+1/2-1/3+...+1/2007-1/2008
=1-1/2008
=2007/2008
请观察没一项绝对值中的数,会发现左边的数小于右边的数,
所以 ,原式=(1-1/2)+(1/2-1/3)+(1/3-1/4)+。。。。+(1/2007-1/2008)
=1-1/2+1/2-1/3+1/3-1/4+。。。。+1/2007-1/2008
=1-1/2008=2007/2008
因为绝对值号里面都是小数减大数,可以去掉绝对值号,算式变成:
1-1/2+1/2-1/3+1/3-1/4+……-1/2008
答案为1-1/2008=2007/2008