a,
`3x(x-2)-x+2=0`
`<=>3x(x-2)-(x-2)=0`
`<=>(x-2)(3x-1)=0`
`<=>`\(\left[ \begin{array}{l}x=2\\x=1/3\end{array} \right.\)
b,
`x(x-4)-2x+8=0`
`<=>x(x-4)-2(x-4)`
`<=>(x-4)(x-2)`
`<=>`\(\left[ \begin{array}{l}x=2\\x=4\end{array} \right.\)
c,
`3x(x+5)-3x-15=0`
`<=>3x(x+5)-3(x+5)=0`
`<=>(x+5)(3x-3)=0`
`<=>`\(\left[ \begin{array}{l}x=-5\\x=1\end{array} \right.\)
d,
`(2x-1)^2-(x-3)^2=0`
`<=>(2x-1-x+3)(2x-1+x-3)=0`
`<=>(x+2)(3x-4)=0`
`<=>`\(\left[ \begin{array}{l}x=-2\\x=4/3\end{array} \right.\)
e,
`x^4-x^3+x^2-x=0`
`<=>x^3(x-1)+x(x-1)=0`
`<=>(x-1)(x^3+1)=0`
`<=>(x-1)(x+1)(x^2-x+1)`
Vì `x^2-x+1=(x-1/2)^2+3/4>0∀x`
`<=>`\(\left[ \begin{array}{l}x=1\\x=-1\end{array} \right.\)
f,
`x^2+4x-12=0`
`<=>x^2-2x+6x-12=0`
`<=>x(x-2)+6(x-2)=0`
`<=>(x-2)(x+6)=0`
`<=>`\(\left[ \begin{array}{l}x=2\\x=-6\end{array} \right.\)
