ОДЗ:
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0} \atop {2x-1>0}} \right. \to \left \{ {{x>4} \atop {x>0.5}} \right. \to x>4" alt=" \left \{ {{x-4>0} \atop {2x-1>0}} \right. \to \left \{ {{x>4} \atop {x>0.5}} \right. \to x>4" align="absmiddle" class="latex-formula">
Воспользуемся свойством логарифмов
D=b²-4ac=121
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- не удовлетворяет ОДЗ
Ответ: 5.