`a, (x-2)(2x+4) = 0`
`⇔`\(\left[ \begin{array}{l}x-2=0\\2x+4=0\end{array} \right.\)
`⇔`\(\left[ \begin{array}{l}x=2\\x=-2\end{array} \right.\)
Vậy `S = {\pm2}`
`b, 3x + 8 = 12`
`⇔ 3x = 4`
`⇔ x = 4/3`
Vậy `S = {4/3}`
`c, 3x - 6 = 0`
`⇔ 3x = 6`
`⇔ x = 2`
Vậy `S ={2}`
`d, (x-2)(3x+5)(2x-1)=0`
`⇔`\(\left[ \begin{array}{l}x-2=0\\3x+5=0\\2x-1=0\end{array} \right.\)
`⇔`\(\left[ \begin{array}{l}x=2\\x=-\dfrac{5}{3}\\x=\dfrac{1}{2}\end{array} \right.\)
Vậy `S = {2,-5/3,1/2}`