Đáp án:
d. x=5
Giải thích các bước giải:
\(\begin{array}{l}
a.\left| {2x - 1} \right| = 2x - 1\\
\to \left[ \begin{array}{l}
2x - 1 = 2x - 1\left( {ld} \right)\\
2x - 1 = - 2x + 1
\end{array} \right.\\
\to 4x = 2\\
\to x = \dfrac{1}{2}\\
b.\left| {5 - x} \right| = 5 - x\\
\to 5 - x = - 5 + x\\
\to 2x = 10\\
\to x = 5\\
c.\left| {x + 3} \right| = - x - 3\\
\to \left[ \begin{array}{l}
x + 3 = - x - 3\\
x + 3 = x + 3\left( {ld} \right)
\end{array} \right.\\
\to 2x = - 6\\
\to x = - 3\\
d.\left| {x + 1} \right| + \left| {x + 4} \right| = 3x\\
\to \left[ \begin{array}{l}
x + 1 + x + 4 = 3x\left( {DK:x \ge - 1} \right)\\
- x - 1 + x + 4 = 3x\left( {DK: - 1 > x \ge - 4} \right)\\
x + 1 + x + 4 = - 3x\left( {DK: - 4 > x} \right)
\end{array} \right.\\
\to \left[ \begin{array}{l}
x = 5\\
x = 1\left( l \right)\\
x = - 1\left( l \right)
\end{array} \right.
\end{array}\)
