`f)`

ĐKXĐ : `x\ne-3`

`(x^2+x-6)/(x+3)=x^2-2x`

`=>x^2+x-6=(x^2-2x)(x+3)`

`<=>x^2-2x+3x-6=x(x-2)(x+3)`

`<=>x(x-2)+3(x-2)=x(x-2)(x+3)`

`<=>(x-2)(x+3)=x(x-2)(x+3)`

`<=>(x-2)(x+3)-x(x-2)(x+3)=0`

`<=>(x-2)[(x+3)-x(x+3)]=0`

`<=>(x-2)(x+3)(1-x)=0`

`<=>x-2=0` hoặc `x+3=0` hoặc `1-x=0`

`<=>x=2(tm)` hoặc `x=-3(ktm)` hoặc `x=1(tm)`

Vậy `S={2;1}`

`#owen`