Tìm x: \(2. | x | − 3 = 7 − ( − 4 ) \)
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Lời giải:
Báo sai\(\begin{array}{l} \begin{array}{*{20}{l}} {{\mkern 1mu} 2.\left| x \right| - 3 = 7 - \left( { - 4} \right)}\\ {{\mkern 1mu} {\mkern 1mu} {\mkern 1mu} {\mkern 1mu} {\mkern 1mu} 2.\left| x \right| - 3 = 11}\\ {{\mkern 1mu} {\mkern 1mu} {\mkern 1mu} {\mkern 1mu} {\mkern 1mu} 2.\left| x \right| = 11 + 3}\\ {{\mkern 1mu} {\mkern 1mu} {\mkern 1mu} {\mkern 1mu} {\mkern 1mu} 2.\left| x \right| = 14}\\ {{\mkern 1mu} {\mkern 1mu} {\mkern 1mu} {\mkern 1mu} {\mkern 1mu} {\mkern 1mu} {\mkern 1mu} {\mkern 1mu} {\mkern 1mu} \left| x \right| = 14:2}\\ {{\mkern 1mu} {\mkern 1mu} {\mkern 1mu} {\mkern 1mu} {\mkern 1mu} {\mkern 1mu} {\mkern 1mu} {\mkern 1mu} {\mkern 1mu} \left| x \right| = 7} \end{array}\\ \to \left[ \begin{array}{l} x = - 7\\ x = 7 \end{array} \right. \end{array}\)
Vậy x=7 hoặc x=−7