Đáp án:
14) \(\left[ \begin{array}{l}
x = 11\\
x = - 15
\end{array} \right.\)
Giải thích các bước giải:
\(\begin{array}{l}
9)5x - 16 = 40 + x\\
\to 4x = 56\\
\to x = 14\\
10)7x - 4 = 20 + 3x\\
\to 4x = 24\\
\to x = 6\\
12)17 - x = 7 - 6x\\
\to 5x = - 10\\
\to x = - 2\\
13)\left( {x + 5} \right)\left( {x - 4} \right) = 0\\
\to \left[ \begin{array}{l}
x + 5 = 0\\
x - 4 = 0
\end{array} \right.\\
\to \left[ \begin{array}{l}
x = - 5\\
x = 4
\end{array} \right.\\
14)\left| {x + 2} \right| + 7 = - 10\left( { - 2} \right)\\
\to \left| {x + 2} \right| = 20 - 7\\
\to \left| {x + 2} \right| = 13\\
\to \left[ \begin{array}{l}
x + 2 = 13\\
x + 2 = - 13
\end{array} \right.\\
\to \left[ \begin{array}{l}
x = 11\\
x = - 15
\end{array} \right.
\end{array}\)
