1/
a/
$-13=13.(-1)$
$b/-15=(-3).5$
$c/-27=(-3).9$
2/
a/
$11x=55⇔x=55:11⇔x=5$
vậy $x=5$
b/
$12x=144$
$⇔x=144:12$
$⇔x=12$
vậy $x=12$
c/
$-3x=-12$
$⇔x=(-12):(-3)$
$⇔x=4$
$vậy$ $x=4$
d/
$0x=4$
$⇔x=0$
$vậy$ $x=04
e/
$2x=6$
$⇔x=6:2$
$⇔x=3$
$vậy$ $x=3$
$f/(x+5)(x-4)=0$
⇔\(\left[ \begin{array}{l}x+5=0\\x-4=0\end{array} \right.\)
⇔\(\left[ \begin{array}{l}x=-5\\x=4\end{array} \right.\)
$vậy$ $x=-5$ $hoặc$ $x=4$
g/
$(x-1)(x-3)=0$
⇔\(\left[ \begin{array}{l}x-1=0\\x-3=0\end{array} \right.\)
⇔\(\left[ \begin{array}{l}x=1\\x=3\end{array} \right.\)
vậy x=1 hoặc x=3
h/
$(3-x)(x-3)=0$
⇔\(\left[ \begin{array}{l}3-x=0\\x-3=0\end{array} \right.\)
⇔\(\left[ \begin{array}{l}x=3\\x=3\end{array} \right.\)
Vậy$ x=3$
e/
$x(x+1)=0$
⇔\(\left[ \begin{array}{l}x=0\\x+1=0\end{array} \right.\)
⇔\(\left[ \begin{array}{l}x=0\\x=-1\end{array} \right.\)
Vậy $x=0$ hoặc $x=-1$
