Tìm ba phân số:

a) Bằng phân số \(\frac{7}{9}\);                     b) Bằng phân số \(\frac{{27}}{{36}}\);

Hướng Dẫn Giải

a) \(\frac{7}{9} = \frac{{7 \times 2}}{{9 \times 2}} = \frac{{14}}{{18}}\);                              \(\frac{7}{9} = \frac{{7 \times 3}}{{9 \times 3}} = \frac{{21}}{{27}}\);                           \(\frac{7}{9} = \frac{{7 \times 10}}{{9 \times 10}} = \frac{{70}}{{90}}\)

b) \(\frac{{27}}{{36}} = \frac{{27:3}}{{36:3}} = \frac{9}{{12}}\);              \(\frac{{27}}{{36}} = \frac{{27:9}}{{36:9}} = \frac{3}{4}\);                               \(\frac{{27}}{{36}} = \frac{{27 \times 2}}{{36 \times 2}} = \frac{{54}}{{72}}\)