`1)`

`3x^2-5x=3x-5`

`<=>3x^2-5x-3x+5=0`

`<=>3x^2-8x+5=0`

`<=>3x^2-3x-5x+5=0`

`<=>(3x^2-3x)-(5x-5)=0`

`<=>3x(x-1)-5(x-1)=0`

`<=>(x-1)(3x-5)=0`

`<=>x-1=0` hoặc `3x-5=0`

`<=>x=1` hoặc `x=5/3`

Vậy `S={1;5/3}`

`2)`

`9x^2-1=6x-2`

`<=>9x^2-6x-1+2=0`

`<=>9x^2-6x+1=0`

`<=>(3x)^2-2.3x.1+1=0`

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

`<=>3x-1=0`

`<=>3x=1`

`<=>x=1/3`

Vậy `x=1/3`

`3)`

`15x^2-3x=1-5x`

`<=>15x^2-3x+5x-1=0`

`<=>15x^2+2x-1=0`

`<=>15x^2+5x-3x-1=0`

`<=>(15x^2+5x)-(3x+1)=0`

`<=>5x(3x+1)-(3x+1)=0`

`<=>(3x+1)(5x-1)=0`

`<=>3x+1=0` hoặc `5x-1=0`

`<=>x=-1/3` hoặc `x=1/5`

Vậy `S={-1/3;1/5}`

`4)`

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

`<=>18x+6x^2-12-4x-3x+2=0`

`<=>6x^2+11x-10=0`

`<=>6x^2+15x-4x-10=0`

`<=>3x(2x+5)-2(2x+5)=0`

`<=>(2x+5)(3x-2)=0`

`<=>2x-5=0` hoặc `3x+2=0`

`<=>x=-5/2` hoặc `x=2/3`

Vậy `S={-5/2;2/3}`

`5)`

`7x-2x^2=2x-7`

`<=>2x-7-7x+2x^2=0`

`<=>2x^2-5x-7=0`

`<=>2x^2+2x-7x-7=0`

`<=>(2x^2+2x)-(7x+7)=0`

`<=>2x(x+1)-7(x+1)=0`

`<=>(x+1)(2x-7)=0`

`<=>x+1=0` hoặc `2x-7=0`

`<=>x=-1` hoặc `x=7/2`

Vậy `S={-1;7/2}`

`6)`

`3x^2-3=x-1`

`<=>3x^2-x-3+1=0`

`<=>3x^2-x-2=0`

`<=>3x^2-3x+2x-2=0`

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

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

`<=>x-1=0` hoặc `3x+2=0`

`<=>x=1` hoặc `x=-2/3`

Vậy `S={1;-2/3}`

`7)`

`6x-2=3x^2-x`

`<=>3x^2-x-6x+2=0`

`<=>3x^2-7x+2=0`

`<=>3x^2-6x-x+2=0`

`<=>(3x^2-6x)-(x-2)=0`

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

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

`<=>3x-1=0` hoặc `x-2=0`

`<=>x=1/3` hoặc `x=2`

Vậy `S={1/3;2}`

`8)`

`7x^2+4x=7x+4`

`<=>7x^2+4x-7x-4=0`

`<=>7x^2-3x-4=0`

`<=>7x^2-7x+4x-4=0`

`<=>7x(x-1)+4(x-1)=0`

`<=>(x-1)(7x+4)=0`

`<=>x-1=0` hoặc `7x+4=0`

`<=>x=1` hoặc `x=-4/7`

Vậy `S={1;-4/7}`

`#owen`