Làm bài 3 giúp mình với mình đang cần

$1,3x-9=0$

$⇔3x=9$

$⇔x=3$

$2,x^2-2x=0$

$⇔x(x-2)=0$

\(⇔\left[ \begin{array}{l}x=0\\x-2=0\end{array} \right.\)

\(⇔\left[ \begin{array}{l}x=0\\x=2\end{array} \right.\)

$3,x^{2}+2x+1=0$

$⇔(x+1)^2=0$

$⇔x=-1$ 

$4,x(x-1)+2(x-1)=0$

$⇔(x-1)(x+2)=0$

\(⇔\left[ \begin{array}{l}x-1=0\\x+2=0\end{array} \right.\)

\(⇔\left[ \begin{array}{l}x=1\\x=-2\end{array} \right.\)