\(\dfrac{7}{12}=\dfrac{21}{36};\dfrac{4}{9}=\dfrac{16}{36}\)
\(taco:\dfrac{21}{36}>\dfrac{16}{36}\)
\(\Rightarrow\dfrac{7}{12}>\dfrac{4}{9}\)
a) So sánh: \(\dfrac{7}{12}\) và \(\dfrac{4}{9}\)
MSC: 36
\(\dfrac{7}{12}=\dfrac{7\times3}{12\times3}=\dfrac{21}{36}\) ; \(\dfrac{4}{9}=\dfrac{4\times4}{9\times4}=\dfrac{16}{36}\)
Vậy \(\dfrac{7}{12}>\dfrac{4}{9}\) ( vì \(\dfrac{21}{36}>\dfrac{16}{36}\) )
b) So sánh \(\dfrac{25}{60};\dfrac{7}{16};\)\(\dfrac{3}{8}\)
MSC: 240
\(\dfrac{25}{60}=\dfrac{25\times4}{60\times4}=\dfrac{100}{240}\)
\(\dfrac{7}{16}=\dfrac{7\times15}{16\times15}=\dfrac{105}{240}\)
\(\dfrac{3}{8}=\dfrac{3\times30}{8\times30}=\dfrac{90}{240}\)
Vậy \(\dfrac{7}{16}>\dfrac{25}{60}>\dfrac{3}{8}\)
