Giải thích các bước giải:
\(\begin{array}{l}
a.\left[ \begin{array}{l}
x = 0\\
x = - 3
\end{array} \right.\\
b.\left[ \begin{array}{l}
x - 2 = 0\\
5 - x = 0
\end{array} \right. \to \left[ \begin{array}{l}
x = 2\\
x = 5
\end{array} \right.\\
c.x - 1 = 0\left( {do:{x^2} + 1 > 0\forall x} \right)\\
\to x = 1\\
d. - 12x + 60 + 21 - 7x = 5\\
\to - 19x = - 76\\
\to x = 4\\
e.30x + 60 - 6x + 30 - 24x = 100\\
\to 0x = 10\left( {vô lí} \right)
\end{array}\)
⇒ Phương trình vô nghiệm
\(\begin{array}{l}
f.\left[ \begin{array}{l}
2x - 5 = 13\\
2x - 5 = - 13
\end{array} \right. \to \left[ \begin{array}{l}
x = 9\\
x = - 4
\end{array} \right.\\
g.\left[ \begin{array}{l}
7x + 3 = 66\\
7x + 3 = - 66
\end{array} \right. \to \left[ \begin{array}{l}
x = 9\\
x = - \frac{{69}}{7}
\end{array} \right.\\
h.\left| {5x - 2} \right| \le 0\\
\Leftrightarrow 5x - 2 = 0\\
\Leftrightarrow x = \frac{2}{5}
\end{array}\)
