Đáp án:
x=8
Giải thích các bước giải:
\(\begin{array}{l}
\left| {x + 1} \right| + \left| {x - 2} \right| + \left| {x + 7} \right| = 5x - 10\\
\to \left[ \begin{array}{l}
x + 1 + x - 2 + x + 7 = 5x - 10\left( {DK:x \ge 2} \right)\\
x + 1 - x + 2 + x + 7 = 5x - 10\left( {DK:2 > x \ge - 1} \right)\\
- x - 1 - x + 2 + x + 7 = 5x - 10\left( {DK: - 1 > x \ge - 7} \right)\\
- x - 1 - x + 2 - x - 7 = 5x - 10\left( {DK: - 7 > x} \right)
\end{array} \right.\\
\to \left[ \begin{array}{l}
2x = 16\\
4x = 20\\
6x = 18\\
8x = 4
\end{array} \right.\\
\to \left[ \begin{array}{l}
x = 8\left( {TM} \right)\\
x = 5\left( l \right)\\
x = 3\left( l \right)\\
x = \dfrac{1}{2}\left( l \right)
\end{array} \right.\\
KL:x = 8
\end{array}\)
