>; <; = ?
So sánh hai phân số rồi điền dấu thích hợp.
a) $\frac{{24}}{{173}} < \frac{{26}}{{173}}$
Ta có: $\frac{{45}}{{100}} = \frac{{45:5}}{{100:5}} = \frac{9}{{20}}$, nên: $\frac{{45}}{{100}} = \frac{9}{{20}}$
Ta có: $\frac{{16}}{{21}} = \frac{{16 \times 3}}{{21 \times 3}} = \frac{{48}}{{63}}$, nên: $\frac{{43}}{{63}} < \frac{{16}}{{21}}$
b) Ta có: $\frac{{18}}{{19}} = \frac{{18 \times 2}}{{19 \times 2}} = \frac{{36}}{{38}}$, nên: $\frac{{18}}{{19}} < \frac{{37}}{{38}}$
Ta có: $\frac{2}{3} = \frac{{2 \times 16}}{{3 \times 16}} = \frac{{32}}{{48}}$, nên $\frac{{32}}{{48}} = \frac{2}{3}$
Ta có: $\frac{4}{5} = \frac{{4 \times 25}}{{5 \times 25}} = \frac{{100}}{{125}}$, nên: $\frac{{126}}{{125}} > \frac{4}{5}$
c) $\frac{{35}}{{39}} < 1$
Ta có: $\frac{{19}}{{19}} = 1$, nên $\frac{{19}}{{19}} > \frac{{35}}{{36}}$
Ta có: $\frac{{27}}{{29}} < 1;{\text{ }}\frac{{29}}{{27}} > 1$, nên $\frac{{27}}{{29}} < \frac{{29}}{{27}}$
