`1//x(5-2x)+2x(x-1)=15`
`<=>5x-2x^2+2x^2-2x=15`
`<=>3x=15`
`<=>x=5` Vậy `S={5}`
`2//12x^2-4x(3x-5)=10x-17`
`<=>12x^2-12x^2+20x=10x-17`
`<=>10x=-17`
`<=>x=-17/10` Vậy `S={-17/10}`
`3//4x(x-5)-(x-1)(4x-3)=5`
`<=>4x^2-20x-4x^2+3x+4x-3=5`
`<=>-13x=8`
`<=>x=-8/13` Vậy `S={-8/13}`
`4//(x-5)(x-1)=(x-1)(x-2)`
`<=>(x-1)(x-5-x+2)=0`
`<=>(x-1).(-3)=0`
`<=>x-1=0`
`<=>x=1` Vậy `S={1}`