Đáp án:
a) \(x=3\)
b) \(x=4\)
Giải thích các bước giải:
\(\begin{array}{l}
\left| {x + 2} \right| = 2x - 1\,DK\;:\; x
\ge \frac{1}{2}\\
\Leftrightarrow \left[ \begin{array}{l}
x + 2 = 2x - 1\\
x + 2 = 1 - 2x
\end{array} \right. \Leftrightarrow \left[ \begin{array}{l}
x = 3\left( tmdk \right)\\
x = - \frac{1}{3}\left( ktmdk \right)
\end{array} \right.\\
\sqrt {2x + 1} = x - 1\\
\Leftrightarrow \left\{ \begin{array}{l}
x \ge 1\\
2x + 1 = {x^2} - 2x + 1
\end{array} \right. \Leftrightarrow \left\{ \begin{array}{l}
x \ge 1\\
{x^2} - 4x = 0
\end{array} \right.\\
\Leftrightarrow \left\{ \begin{array}{l}
x \ge 1\\
\left[ \begin{array}{l}
x = 0\\
x = 4
\end{array} \right.
\end{array} \right. \Leftrightarrow x = 4
\end{array}\)
