Đáp án: `x=2000`
Giải thích các bước giải:
`(2014-x)/14 + (2013-x)/13 = (2012-x)/12 + (2011-x)/11`
`⇔(2014-x)/14 -1+ (2013-x)/13-1 = (2012-x)/12 -1+ (2011-x)/11-1`
`⇔(2014-x)/14-14/14+(2013-x)/13-13/13=(2012-x)/12-12/12+(2011-x)/11-11/11`
`⇔(2014-x-14)/14+(2013-x-13)/13=(2012-x-12)/12+(2011-x-11)/11`
`⇔(2000-x)/14 +(2000-x)/13 = (2000-x)/12+(2000-x)/11`
`⇔(2000-x)/14 +(2000-x)/13 - (2000-x)/12 - (2000-x)/11=0`
`⇔(2000-x)(1/14 +1/13 - 1/12 -1/11)=0`
Ta có: `1/14 +1/13 - 1/12 -1/11 \ne 0`
`⇒2000-x=0`
`⇒x=2000`
Vậy `x=2000`
