a)

* Rút gọn : 21/56 = 3/8 ; 60/96 = 5/8

Vì 3 < 5 

=> 3/8 < 5/8 ( hay 21/56 < 60/96 )

Vậy 21/56 < 60/96

\(\text{a)}\)

\(\text{Ta có: }\text{ }\frac{21}{56}=\frac{21:7}{56:7}=\frac{3}{8}\text{ và }\frac{60}{96}=\frac{60:12}{96:12}=\frac{5}{8}\)

       \(\Rightarrow\frac{21}{56}< \frac{60}{96}\left(\frac{3}{8}< \frac{5}{8}\right)\)

\(\text{b)}\)

\(\text{Ta có: }\frac{75}{100}=\frac{75:25}{100:25}=\frac{3}{4}\text{ và }\frac{45}{36}=\frac{45:9}{36:9}=\frac{5}{4}\)    

       \(\Rightarrow\frac{75}{100}< \frac{45}{36}\left(\frac{3}{4}< \frac{5}{4}\right)\)

\(\text{# học tốt #}\)

thanks nha

SHDlUIWDHULyasgdyuWGEDDed

a: 90/126=5/7<6/7

b: 70/84=5/6

35/42=5/6

=>70/84=35/42

a)\(\dfrac{90}{126}=\dfrac{5}{7}< \dfrac{6}{7}\Leftrightarrow\cdot\dfrac{90}{126}< \dfrac{6}{7}\)

b)\(\dfrac{70}{84}=\dfrac{5}{6};\dfrac{35}{42}=\dfrac{5}{6}\Leftrightarrow\cdot\dfrac{70}{84}=\dfrac{35}{42}\)

a,\(\frac{16}{36}\)=\(\frac{4}{9}\)                         \(\frac{20}{45}\)=\(\frac{4}{9}\)                         \(\frac{28}{63}\)=\(\frac{4}{9}\)

suy ra: các phân số này bằng nhau

b,\(\frac{45}{65}\)=\(\frac{9}{13}\)                            \(\frac{48}{52}\)=\(\frac{12}{13}\)               \(\frac{2121}{1313}\)=\(\frac{21}{13}\)

suy ra tự kết luận

3/4 >2/4

\(\dfrac{6}{12}=\dfrac{6:3}{12:3}=\dfrac{2}{4}\)

\(\dfrac{3}{4}>\dfrac{2}{4}\)

3/4>2/4 nhá bạn 

4/10=2/5

1/5<2/5

ok bạn nhé