a) x . ( x + 7 ) = 0
<=> \(\left[ \begin{array}{l}x=0\\x+7=0\end{array} \right.\)
<=> \(\left[ \begin{array}{l}x=0\\x=-7\end{array} \right.\)
Vậy x = 0 hoặc x = -7 .
b) ( x + 12 ) . ( x - 3 ) = 0
<=> \(\left[ \begin{array}{l}x+12=0\\x-3=0\end{array} \right.\)
<=> \(\left[ \begin{array}{l}x=-12\\x=3\end{array} \right.\)
Vậy x = -12 hoặc x = 3.
c) ( -x + 5 ) . ( 3 - x ) = 0
<=> \(\left[ \begin{array}{l}-x+5=0\\3-x = 0\end{array} \right.\)
<=> \(\left[ \begin{array}{l}x=5\\x=3\end{array} \right.\)
Vậy x = 5 hoặc x = 3.
d) x . ( 2 + x ) . ( 7 - x ) = 0
<=>\(\left[ \begin{array}{l}x=0\\2+x=0\\7-x=0\end{array} \right.\)
<=> \(\left[ \begin{array}{l}x=0\\x=-2\\x=7\end{array} \right.\)
Vậy x = 0 hoặc x = -2 hoặc x = 7
e) ( x - 1 ) ( x + 2 ) ( -x - 3 ) = 0
<=> \(\left[ \begin{array}{l}x-1=0\\x+2=0\\-x-3 =0\end{array} \right.\)
<=> \(\left[ \begin{array}{l}x=1\\x=-2\\x=-3\end{array} \right.\)
Vậy x = 1 hoặc x = -2 hoặc x = -3.
