$\begin{array}{l} \left| a \right| = \left| b \right|\\ \Leftrightarrow \left[ \begin{array}{l} a = b\\ a = – b \end{array} \right. \end{array}$ $\begin{array}{l} \left| {3 – 4x} \right| = \left| {1 + 4x} \right|\\ \Leftrightarrow \left[ \begin{array}{l} 3 – 4x = 1 + 4x\\ 3 – 4x = – \left( {1 + 4x} \right) \end{array} \right.\\ \Leftrightarrow \left[ \begin{array}{l} 8x = 2\\ 3 = – 1(VL) \end{array} \right. \Rightarrow x = \dfrac{1}{4}\\ \Rightarrow S = \left\{ {\dfrac{1}{4}} \right\} \end{array}$ Trả lời
$\begin{array}{l} \left| a \right| = \left| b \right|\\ \Leftrightarrow \left[ \begin{array}{l} a = b\\ a = – b \end{array} \right. \end{array}$
$\begin{array}{l} \left| {3 – 4x} \right| = \left| {1 + 4x} \right|\\ \Leftrightarrow \left[ \begin{array}{l} 3 – 4x = 1 + 4x\\ 3 – 4x = – \left( {1 + 4x} \right) \end{array} \right.\\ \Leftrightarrow \left[ \begin{array}{l} 8x = 2\\ 3 = – 1(VL) \end{array} \right. \Rightarrow x = \dfrac{1}{4}\\ \Rightarrow S = \left\{ {\dfrac{1}{4}} \right\} \end{array}$
Mk trình bày trong hình :