Khoanh vào chữ đặt trước hỗn số:

Hướng Dẫn Giải

\(13 = \frac{{13}}{1} = \frac{{13 \times 3}}{{1 \times 3}} = \frac{{39}}{3}\);                        \(13 = \frac{{13}}{1} = \frac{{13 \times 5}}{{1 \times 5}} = \frac{{65}}{5}\);

\(13 = \frac{{13}}{1} = \frac{{13 \times 10}}{{1 \times 10}} = \frac{{130}}{{10}}\);                            \(13 = \frac{{13}}{1} = \frac{{13 \times 17}}{{1 \times 17}} = \frac{{221}}{{17}}\);

Hướng Dẫn Giải

\(\frac{5}{7} = \frac{{5 \times 2}}{{7 \times 2}} = \frac{{10}}{{14}}\);                              \(\frac{5}{7} = \frac{{5 \times 4}}{{7 \times 4}} = \frac{{20}}{{28}}\);

\(\frac{5}{7} = \frac{{5 \times 5}}{{7 \times 5}} = \frac{{25}}{{35}}\);                              \(\frac{5}{7} = \frac{{5 \times 15}}{{7 \times 15}} = \frac{{75}}{{105}}\);