a) Hãy giải thích vì sao ba phân số \(\dfrac{{12}}{{18}},\dfrac{4}{6},\dfrac{2}{3}\) bằng nhau.
b) Điền số thích hợp vào ô trống :
\(\eqalign{
& \frac{{12}}{{18}} = \frac{{12:...}}{{18:...}} = \frac{6}{9}\frac{6}{9} = \frac{{6:...}}{{9:...}} = \frac{2}{3} \cr
& \frac{{12}}{{18}} = \frac{{12:...}}{{18:...}} = \frac{4}{6}\frac{4}{6} = \frac{{4:...}}{{6:...}} = \frac{2}{3} \cr} \)
a) Ba phân số: \(\dfrac{{12}}{{18}};\dfrac{4}{6};\dfrac{2}{3}\) bằng nhau.
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Giải thích:
\(\eqalign{
& \frac{4}{6} = \frac{{4:2}}{{6:2}} = \frac{2}{3}; \cr
& \frac{{12}}{{18}} = \frac{{12:6}}{{18:6}} = \frac{2}{3} \cr} \)
Vậy \(\dfrac{{12}}{{18}} = \dfrac{4}{6} = \dfrac{2}{3}.\)
b)
\(\eqalign{
& \frac{{12}}{{18}} = \frac{{12:2}}{{18:2}} = \frac{6}{9}\frac{6}{9} = \frac{{6:3}}{{9:3}} = \frac{2}{3} \cr
& \frac{{12}}{{18}} = \frac{{12:3}}{{18:3}} = \frac{4}{6}\frac{4}{6} = \frac{{4:2}}{{6:2}} = \frac{2}{3} \cr} \)