`#Sad`
`a)`
`3x^2-5x+2 = 0`
`⇔ 3x^2-3x-2x+2 = 0`
`⇔ (3x^2-3x)-(2x-2) = 0`
`⇔ 3x(x-1)-2(x-1) = 0`
`⇔ (3x-2)(x-1) = 0`
`⇔` \(\left[ \begin{array}{l}3x-2=0\\x-1=0\end{array} \right.\)
`⇔` \(\left[ \begin{array}{l}3x=2\\x=1\end{array} \right.\)
`⇔` \(\left[ \begin{array}{l}x=\dfrac{2}{3}\\x=1\end{array} \right.\)
`\text{Vậy S=}` `{2/3; 1}`
`b)`
`2x^2+3x-5 = 0`
`⇔ 2x^2+5x-2x-5 = 0`
`⇔ (2x^2-2x)+(5x-5) = 0`
`⇔ 2x(x-1)+5(x-1) = 0`
`⇔ (2x+5)(x-1) = 0`
`⇔` \(\left[ \begin{array}{l}2x+5=0\\x-1=0\end{array} \right.\)
`⇔` \(\left[ \begin{array}{l}2x=-5\\x=1\end{array} \right.\)
`⇔` \(\left[ \begin{array}{l}x=-\dfrac{5}{2}\\x=1\end{array} \right.\)
`\text{Vậy S=}` `{-(5)/(2); 1}`
