Алгебра: Log1/7(4x+1)<-2 помогитее

Решите задачу:

$\log_\frac{1}{7} (4x+1)\ \textless \ -2, \\ \left \{ {{4x+1\ \textgreater \ 0,} \atop {4x+1\ \textgreater \ (\frac{1}{7})^{-2};}} \right. \\ 4x+1\ \textgreater \ 49, \\ 4x\ \textgreater \ 48, \\ x\ \textgreater \ 12$