Bài 3:
c, $x(x+2)=0$
$⇔$\(\left[ \begin{array}{l}x=0\\x+2=0\end{array} \right.\)
$⇔$\(\left[ \begin{array}{l}x=0\\x=-2\end{array} \right.\)
Vậy $x=0$ hoặc $x=-2$
d, $(x+5)(x-3)=0$
$⇔$\(\left[ \begin{array}{l}x+5=0\\x-3=0\end{array} \right.\)
$⇔$\(\left[ \begin{array}{l}x=-5\\x=3\end{array} \right.\)
Vậy $=-5$ hoặc $x=3$