Đáp án`+`Giải thích các bước giải`:`

`d)`

`2x+20/(15.17)+20/(17.19)+....+20/(61.63)+20/(63.65)=(-1)/25`

`=>2x+10(2/(15.17)+2/(17.19)+....+2/(61.63)+2/(63.65))=-1/25`

`=>2x+10(1/15-1/17+1/17-1/19+....+1/63-1/65)=-1/25`

`=>2x+10(1/15-1/65)=-1/25`

`=>2x+10(65/195-15/195)=-1/25`

`=>2x + 10 . 50/195=-1/25`

`=>2x+100/39=-1/25`

`=>2x=-1/25-100/39`

`=>2x=-39/975-2500/975=-2539/975`

`=>x=-2539/975 : 2=-2539/1950`

Vậy `:x=-2539/1950`

`e)`

`(3/4+3/7-3/12+3/26)/(11/4+11/7-11/12+11/36) . x=12`

`=>(3(1/4+1/7-1/12+1/36))/(11(1/4+1/7-1/12+1/36)) x=12`

`=>3/11 x=12`

`=>x=12 : 3/11=44`

Vậy `:x=44`