Đáp án:+Giải thích các bước giải:

 Ta có:

`D=|x+3|+5|6x+1|+|x-1|+3`

Nếu `x<-3` thì:

`D=-(x+3)+5[-(6x+1)]+[-(x-1)]+3`

`=-x-3-30x-5-x+1+3`

`=-32x-4`

Nếu `-3≤x<-1/6` thì:

`D=(x+3)+5[-(6x+1)]+[-(x-1)]+3`

`=x+3-30x-5-x+1+3`

`=-30x+2`

Nếu `-1/6≤x<1` thì:

`D=(x+3)+5(6x+1)+[-(x-1)]+3`

`=x+3+30x+5-x+1+3`

`=30x+12`

Nếu `x≥1` thì:

`D=(x+3)+5(6x+1)+(x-1)+3`

`=x+3+30x+5+x-1+3`

`=32x+10`

Vậy `x<-3⇔D=-32x-4`

`-3≤x<-1/6⇔D=-30x+2`

`-1/6≤x<1⇔D=30x+12`

`x≥1⇔D=32x+10`