Đề bài

Giải các bất phương trình lôgarit sau:

a) ${\rm{lo}}{{\rm{g}}_3}\left( {2x + 1} \right) \ge 2$;

b) ${\rm{lo}}{{\rm{g}}_2}\left( {3x - 1} \right) < {\rm{lo}}{{\rm{g}}_2}\left( {9 - 2x} \right)$;

c) ${\rm{lo}}{{\rm{g}}_{\frac{1}{2}}}\left( {x + 1} \right) \le {\rm{lo}}{{\rm{g}}_{\frac{1}{2}}}\left( {4\dot x - 5} \right)$;

d) ${\rm{lo}}{{\rm{g}}_2}\left( {2x - 1} \right) \le {\rm{lo}}{{\rm{g}}_4}{(x + 1)^2}$.