`***`Lời giải`***`
a)
`3(x-1)^2-3x(x-5)=2 `
`<=>3(x^2-2x+1)-3x^2+15x=2 `
`<=>3x^2-6x+3-3x^2+15x=2 `
`<=>3x^2-6x-3x^2+15x=2-3 `
`<=>9x=-1 `
`<=>x=-1/9`
Vậy `S={-1/9}`
b)
`4x^2-12x=-9 `
`<=>4x^2-12x+9=0 `
`<=>4x^2-6x-6x+9=0 `
`<=>2x(2x-3)-3(2x-3)=0 `
`<=>(2x-3)^2=0 `
`<=>2x-3=0 `
`<=>2x=3 `
`<=>x=3/2 `
Vậy `S={3/2}`
c)
`(2x-3)^2=(x+5)^2`
`<=>(2x-3)^2-(x+5)^2=0`
`<=>(2x-3+x+5)(2x-3-x-5)=0`
`<=>(3x+2)(x-8)=0`
`<=>`\(\left[ \begin{array}{l}3x+2=0\\x-8=0\end{array} \right.\)
`<=>`\(\left[ \begin{array}{l}3x=-2\\x=8\end{array} \right.\)
`<=>`\(\left[ \begin{array}{l}x=-2/3\\x=8\end{array} \right.\)
Vậy `S={-2/3;8}`
d)
`(x^4-2x^3+4x^2-8x):(x^2+4)-2x=-4`
`<=>x(x^3-2x^2+4x-8):(x^2+4)-2x=-4`
`<=>x(x-2)(x^2+4):(x^2+4)-2x=-4`
`<=>x(x-2)-2x=-4`
`<=>x^2-2x-2x=-4`
`<=>x^2-4x+4=0`
`<=>(x+2)^2=0`
`<=>x+2=0`
`<=>x=-2`
Vậy `S={-2}`
