TL

12/6=2

28/21=4/3

NHÉ

HT

5/7>6/21

18/24>15/25

12/13=1212/1313

\(\dfrac{5}{7}\)>\(\dfrac{6}{21}\)

\(\dfrac{18}{24}\)>\(\dfrac{15}{25}\)

\(\dfrac{12}{13}\)=\(\dfrac{1212}{1313}\)

\(\dfrac{5}{7}=\dfrac{5\times3}{7\times3}=\dfrac{15}{21}\)

Vì \(\dfrac{15}{21}< \dfrac{17}{21}\Rightarrow\dfrac{5}{7}< \dfrac{17}{21}\)

5/7 đã tối giản

17/21 cũng đã tối giản

5/7=15/21

mà 17/21>15/21

=>17/21>5/7

a) 

\(\dfrac{6}{12}=\dfrac{6:6}{12:6}=\dfrac{1}{2}\)

\(\Rightarrow\dfrac{1}{2}=\dfrac{1\times2}{2\times2}=\dfrac{2}{4}\)

Mà \(\dfrac{2}{4}< \dfrac{3}{4}\)

Vậy \(\dfrac{6}{12}< \dfrac{3}{4}\).

b)

\(\dfrac{8}{10}=\dfrac{8:2}{10:2}=\dfrac{4}{5}\)

Mà \(\dfrac{2}{5}< \dfrac{4}{5}\)

Vậy \(\dfrac{2}{5}< \dfrac{8}{10}\).

c)

\(\dfrac{40}{35}=\dfrac{40:5}{35:5}=\dfrac{8}{7}\)

Mà \(\dfrac{8}{7}>\dfrac{6}{7}\)

Vậy \(\dfrac{40}{35}>\dfrac{6}{7}\).

d)

\(\dfrac{8}{16}=\dfrac{8:8}{16:8}=\dfrac{1}{2}\)

Mà \(\dfrac{1}{2}< \dfrac{5}{2}\)

Vậy \(\dfrac{8}{16}< \dfrac{5}{2}\).

`8/16=1/2`

`1<5-> 8/16<5/2`

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Bài 2: So sánh các phân số sau

7/15 > 5/13              11/12 > 7/48        24/35 > 21/7           15/26 > 7/8

Giải cho mình cho mình với sáng mai mình phải nộp bài này rồi

a, \(\dfrac{18}{24}\) = \(\dfrac{3}{4}\)                            \(\dfrac{15}{25}\) = \(\dfrac{3}{5}\) 

     \(\dfrac{3}{4}\)  >  \(\dfrac{3}{5}\) vậy \(\dfrac{18}{24}\) > \(\dfrac{15}{25}\)

b, \(\dfrac{21}{15}\) = \(\dfrac{7}{5}\)                            \(\dfrac{28}{24}\) = \(\dfrac{7}{6}\)

      \(\dfrac{7}{5}\)  >  \(\dfrac{7}{6}\) vậy \(\dfrac{21}{15}\)  >  \(\dfrac{28}{24}\) 

ᵃ, ᵗᵃ ʳᵘ́ᵗ ᵍᵒ̣ⁿ :\(\dfrac{18}{24}=\dfrac{3}{4}\) ;

 ᵗᵃ ʳᵘ́ᵗ ᵍᵒ̣ⁿ :\(\dfrac{15}{25}=\dfrac{3}{5}\)

Vì \(\dfrac{3}{4}>\dfrac{3}{5}\\ \Rightarrow\dfrac{18}{24}>\dfrac{15}{25}\)

ᵇ, ᵗᵃ ʳᵘ́ᵗ ᵍᵒ̣ⁿ :\(\dfrac{21}{15}=\dfrac{7}{5}\\ \dfrac{28}{24}=\dfrac{7}{6}\)

Vì \(\dfrac{7}{5}>\dfrac{7}{6}\\ \Rightarrow\dfrac{21}{15}>\dfrac{28}{24}\)

a) \(\frac{33}{55}=\frac{33:11}{55:11}=\frac{3}{5}\)

Vì \(\frac{3}{5}=\frac{3}{5}\)nên \(\frac{3}{5}=\frac{33}{55}\)

\(\frac{20}{28}=\frac{20:4}{28:4}=\frac{5}{7}\)

Vì \(\frac{5}{7}=\frac{5}{7}\)nên \(\frac{5}{7}=\frac{20}{28}\)

b) \(\frac{6}{21}=\frac{6:3}{21:3}=\frac{2}{7}\)

Vì \(\frac{5}{7}>\frac{2}{7}\)nên \(\frac{5}{7}>\frac{6}{21}\)

\(\frac{1212}{1313}=\frac{1212:101}{1313:101}=\frac{12}{13}\)

VÌ \(\frac{12}{13}=\frac{12}{13}\)nên \(\frac{12}{13}=\frac{1212}{1313}\)

a) Rút gọn 33/55=3/5 => 3/5 = 3/5 hay 3/5=20/28

b) rút gọn 20/28= 5/7=> 5/7= 5/7 hay 5/7 = 20/28

c) rút gọn 6/21 = 2/7=> 5/7 >2/7 hay 5/7>6/21

d) rút gọn 1212/1313 = 12/13=> 12/13=12/13 hay 12/13=1212/1313