Cho a >b> 0, chứng minh 1/a < 1/b.
Giải thích
\(\frac{1}{{\;{\rm{b}}}} - \frac{1}{{\rm{a}}} = \frac{{{\rm{a}} - {\rm{b}}}}{{{\rm{ab}}}} > 0 \Rightarrow \frac{1}{{\;{\rm{b}}}} > \frac{1}{{\rm{a}}}\)
\(\frac{1}{{\;{\rm{b}}}} - \frac{1}{{\rm{a}}} = \frac{{{\rm{a}} - {\rm{b}}}}{{{\rm{ab}}}} > 0 \Rightarrow \frac{1}{{\;{\rm{b}}}} > \frac{1}{{\rm{a}}}\)