a) \(\dfrac{3}{5}=\dfrac{39}{65}\)
Vì : \(\dfrac{39}{65}=\dfrac{39:13}{65:13}=\dfrac{3}{5}\)
b) \(\dfrac{9}{27}và\dfrac{41}{123}\)
Vì : \(\dfrac{9}{27}=\dfrac{1}{3}\)
\(\dfrac{41}{123}=\dfrac{1}{3}\)
==> \(\dfrac{9}{27}=\dfrac{41}{123}\left(=\dfrac{1}{3}\right)\)
c) \(\dfrac{3}{4}và\dfrac{4}{5}\)
Mẫu số chung : 20
\(\dfrac{3}{4}=\dfrac{15}{20}\)
\(\dfrac{4}{5}=\dfrac{16}{20}\)
Vì \(\dfrac{15}{20}< \dfrac{16}{20}\Rightarrow\dfrac{3}{4}< \dfrac{4}{5}\)
d) \(\dfrac{2}{3}và\dfrac{5}{7}\)
Mẫu số chung : 21
\(\dfrac{2}{3}=\dfrac{14}{21}\)
\(\dfrac{5}{7}=\dfrac{15}{21}\)
Vì \(\dfrac{14}{21}< \dfrac{15}{21}\Rightarrow\dfrac{2}{3}< \dfrac{5}{7}\)
