Giúp mình với 30p nữa mình nộp rồiii

`a)` `19-x=4(3-2x)`

`⇔ 19-x=12-8x`

`⇔ -x+8x=12-19`

`⇔ 7x=-7`

`⇔ x=-1`

Vậy `S={-1}`

`b)` `{x-1}/x-3/{x+1}={2x-7}/{x^2+x}`

Đk:`:x\ne0,x\ne-1`

`⇔ {(x-1)(x+1)-3x}/{x(x+1)}={2x-7}/{x(x+1)}`

`⇒ (x-1)(x+1)-3x=2x-7`

`⇔ x^2-1-3x-2x+7=0`

`⇔ x^2-5x+6=0`

`⇔ x^2-2x-3x+6=0`

`⇔ x(x-2)-3(x-2)=0`

`⇔ (x-2)(x-3)=0`

`⇔ x-2=0` hoặc `x-3=0`

`⇔ x=2` `(tm)`   `x=3` `(tm)`

Vậy `S={2;3}`