Đáp án+Giải thích các bước giải:
`n) 1/4 (x+3)=3-1/2 (x+1)-1/3 (x+2)`
`<=>(x+3)/4+(x+2)/3+(x+1)/2-3=0`
`<=>(x-1)/4+(x-1)/3+(x-1)/2=0`
`<=>(x-1)/(1/4+1/3+1/2)=0`
`<=>x-1=0(Vì 1/4+1/3+1/2\ne 0)`
`<=>x=1`
Vậy `x=1`
`r) (3x-11)/11 -1/3=(3x-5)/7-(5x-3)/9`
`<=>[63(3x-11)]/693 -(231)/693=[99(3x-5)]/693-[77(5x-3)]/693`
`<=>189x-693-231=297x-495-385x+231`
`<=>189x-297x+385x=-495+231+693+231`
`<=>277x=660`
`<=>x=660/277`
Vậy`x=660/277`
