Đáp án+Giải thích các bước giải:
` a, 3(x-3)+6=0`
`⇔3(x-3+2)=0`
`⇔3(x-1)=0`
`⇔x-1=0`
`⇔x=1`
`b, x^2-4(x-1)=9(x-2)`
`⇔x^2−4x+4=9x−18`
`⇔x^2−4x+4−9x+18=0 `
`⇔x^2−13x+22=0`
`⇔(x−11)(x−2)=0`
`⇔`\(\left[ \begin{array}{l}x-11=0\\x-2=0\end{array} \right.\)
`⇔`\(\left[ \begin{array}{l}x=11\\x=2\end{array} \right.\)