Điền dấu thích hợp vào ô trốnga) \[\frac{1}{3} + 1.....\frac{2}{3} + 1\]b) \[\frac{1}{4} + \frac{2}{5}.....\frac{1}{5} + \frac{{13}}{{20}}\]

Hướng dẫn giải

a)

Vì: \[\frac{1}{3} < \frac{2}{3}\] Nên: \[\frac{1}{3} + 1 < \frac{2}{3} + 1\]

b)

Ta có:

\[\frac{1}{4} + \frac{2}{5} = \frac{5}{{20}} + \frac{8}{{20}} = \frac{{13}}{{20}}\]

\[\frac{1}{5} + \frac{{13}}{{20}} = \frac{4}{{20}} + \frac{{13}}{{20}} = \frac{{17}}{{20}}\]

So sánh: \[\frac{{13}}{{20}} < \frac{{17}}{{20}}\] hay \[\frac{1}{4} + \frac{2}{5} < \frac{1}{5} + \frac{{13}}{{20}}\]

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