Đáp án:
a) \(\left[ \begin{array}{l}
x = 0\\
x = - 3
\end{array} \right.\)
Giải thích các bước giải:
\(\begin{array}{l}
a)x\left( {x + 3} \right) = 0\\
\to \left[ \begin{array}{l}
x = 0\\
x + 3 = 0
\end{array} \right.\\
\to \left[ \begin{array}{l}
x = 0\\
x = - 3
\end{array} \right.\\
b)\left( {x + 1} \right){x^2} = 0\\
\to \left[ \begin{array}{l}
x + 1 = 0\\
{x^2} = 0
\end{array} \right.\\
\to \left[ \begin{array}{l}
x = - 1\\
x = 0
\end{array} \right.\\
c)5x - 7 \vdots x\\
\to 7 \vdots x\\
\to x \in U\left( 7 \right)\\
\to \left[ \begin{array}{l}
x = 7\\
x = 1
\end{array} \right.
\end{array}\)
