a) \(\dfrac{8}{9}< 1;\dfrac{13}{7}>1\Rightarrow\dfrac{8}{9}< \dfrac{13}{7}\)

b) \(\dfrac{16}{27}>\dfrac{15}{27}>\dfrac{15}{29}\Rightarrow\dfrac{16}{27}>\dfrac{15}{29}\)

a) 13/7

b) 15/29

c) \(\dfrac{181818}{232323}=\dfrac{18x10101}{23x10101}=\dfrac{18}{23}< \dfrac{19}{23}\Rightarrow\dfrac{19}{23}>\dfrac{181818}{232323}\)

\(\dfrac{12}{19}< \dfrac{23}{25}\)

\(\dfrac{21}{27}< \dfrac{23}{25}\)

\(\dfrac{12}{19}< \dfrac{23}{25};\dfrac{21}{27}< \dfrac{23}{25}\)

a) \(\dfrac{12}{19}=\dfrac{19}{19}-\dfrac{7}{19}=1-\dfrac{7}{19}\)

\(\dfrac{23}{25}=\dfrac{25}{25}-\dfrac{2}{25}=1-\dfrac{2}{25}\).

-So sánh: \(\dfrac{7}{19}\) và \(\dfrac{2}{25}\).

\(\dfrac{7}{19}=\dfrac{14}{38};\dfrac{2}{25}=\dfrac{14}{175}\Rightarrow\dfrac{7}{19}>\dfrac{2}{25}\left(\dfrac{14}{38}>\dfrac{14}{175}\right)\)

\(\Rightarrow1-\dfrac{7}{19}< 1-\dfrac{2}{25}\) 

\(\Rightarrow\dfrac{12}{19}< \dfrac{23}{25}\)

-Câu b làm tương tự bạn nhé.

hai phân số nào em nhở?

và phân số nào nữa?

b)21/27<21/25<23/25

-18/91 = -0,19...

-23/114 = -0,20...

mà 0,20...>0,19... nên -0,19... > -0.20...

vậy -18/91 > - 23/114

171717/232323 = 17.10101/23.10101 = 17/23 < 19/23

Rút gọn phân số ta có:

              171717 : 10101 = 17

              232323 : 10101 = 23

Và bằng 17/23 < 19/23.

rút gọn phân số 171717/232323 = 17/23.

vì 17/23 < 19/23 .

Vậy 171717/232323 <19/23

ta có:19/20<20/20 và 20/20<20/21

ta có:1-17/21=21/21-17/21=4/21 

                                               nên 4/21>4/27

         1-23/27=27/27=4/27

ta có:31/29-1=31/29-29/29=2/29

                                                nên 31/29>45/43

        45/43-1=43/43-45/43=2/43

nhớ k mình nha

1919/2323=19/23

191919/232323=19/23

19191919/23232323=19/23

Vậy 19/23=19/23=19/23=19/23

\(\dfrac{36}{23}>\dfrac{36}{24}=\dfrac{3}{2}\)

\(\dfrac{27}{21}< \dfrac{27}{18}=\dfrac{3}{2}\)

\(\Rightarrow\dfrac{36}{23}>\dfrac{27}{21}\)

\(\dfrac{36}{23}>\dfrac{3}{2}\)

\(\dfrac{3}{2}>\dfrac{27}{21}\)

Do đó: \(\dfrac{36}{23}>\dfrac{27}{21}\)

Cảm ơn