Đáp án:
`x=2008`
Giải thích các bước giải:
`x/2008-1/10-1/15-1/21-...-1/120=5/8`
`=>x/2008-(1/10+1/15+1/21+...+1/120)=5/8`
`=>x/2008-(2/20+2/30+2/42+...+2/240)=5/8`
`=>x/2008-(2/4.5+2/5.6+2/6.7+...+2/15.16)=5/8`
`=>x/2008-2(1/4.5+1/5.6+1/6.7+...+1/15.16)=5/8`
`=>x/2008-2(1/4-1/5+1/5-1/6+...+1/15-1/16)=5/8`
`=>x/2008-2(1/4-1/16)=5/8=>x/2008-2(4/16-1/16)=5/8`
`=>x/2008-2. 3/16=5/8=>x/2008-3/8=5/8`
`=>x/2008=5/8+3/8=>x/2008=1=>x/2008=2008/2008=>x=2008`
Vậy `x=2008`
