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 \(\dfrac{8}{16}< \dfrac{5}{2}\).

a) \(\frac{1}{4}\) 

b) \(\frac{2}{7}\)

c) \(\frac{2}{3}\)

à còn phần d là \(\frac{1}{7}\)

a: \(\dfrac{1}{8}\cdot\dfrac{4}{5}:\dfrac{3}{5}=\dfrac{1}{10}\cdot\dfrac{5}{3}=\dfrac{1}{2\cdot3}=\dfrac{1}{6}\)

b: \(=\dfrac{8-3}{12}\cdot\dfrac{6}{5}=\dfrac{6}{12}=\dfrac{1}{2}\)

c: \(=\dfrac{24}{35}:\dfrac{32}{35}=\dfrac{3}{4}\)

d: =63/21+15/21-7/21=71/21

a \(\dfrac{1}{8}\times\dfrac{4}{5}\times\dfrac{10}{6}=\dfrac{1}{6}\)

b \(\left(\dfrac{8}{12}-\dfrac{3}{12}\right)\times\dfrac{6}{5}=\dfrac{5}{12}\times\dfrac{6}{5}=\dfrac{1}{2}\)

c \(\dfrac{24}{35}:\dfrac{32}{35}=\dfrac{24}{35}\times\dfrac{35}{32}=\dfrac{3}{4}\)

d \(\dfrac{63}{21}+\dfrac{15}{21}-\dfrac{7}{21}=\dfrac{71}{21}\)

`1/3 + 1/5 -1/4`

`= 5/15 + 3/15 -1/4`

`= 8/15 -1/4`

`=  17/60`

__

`7/8 -(1/4 + 2/5)`

`= 7/8-1/4 - 2/5`

`= 7/8 - 2/8 -2/5`

`= 5/8 -2/5`

`= 9/40`

__

`5/11-(3/5 -6/11)`

`= 5/11 -3/5 +6/11`

`= (5/11 + 6/11)-3/5`

`= 1 -3/5`

`= 5/5-3/5`

`=2/5`

__

`5/7 - ( 19/35 - 6/15)`

`= 5/7 - 19/35 + 6/15`

`= 25/35 -19/35 + 6/15`

`=6/35 +6/15`

`=4/7`

 `A) 1/3 + 1/5 - 1/4 = 20/60 + 12/60 - 15/60 = 17/60`

` B) 7/8 - ( 1/4 + 2/5 ) = 7/8 - 2/4 -2/5 = 5/8-2/8 = 9/40`

` C) 5/11 - ( 3/5 - 6/11 ) = 5/11 - 3/55 = 25/55 - 3/55 = 22/55=2/5 ` 

` D) 5/7 - ( 19/35 - 6/15 ) = 5/7 - 1/7 = 4/7 `

ai giúp mik với....đi mà......

a) \(6-\dfrac{2}{5}+\dfrac{3}{5}\) x \(3\)

\(=6-\dfrac{2}{5}+\dfrac{9}{5}\)

\(=\dfrac{30}{5}-\dfrac{2}{5}+\dfrac{9}{5}\)

\(=\dfrac{30-2+9}{5}=\dfrac{37}{5}\)

b) \(\left(\dfrac{31}{35}-\dfrac{4}{7}\right)\) x \(\dfrac{8}{7}:2\)

\(=\left(\dfrac{31}{35}-\dfrac{20}{35}\right)\) x \(\dfrac{8}{7}:2\)

\(=\dfrac{11}{35}\) x \(\dfrac{8}{7}:2\)

\(=\dfrac{11}{35}\) x \(\dfrac{8}{7}\) x \(\dfrac{1}{2}\)

\(=\dfrac{\text{11 x 8 x 1}}{\text{ 35 x 7 x 2}}=\dfrac{88}{490}=\dfrac{88}{245}\)  

a) 6−25+356−25+35 x 33

=6−25+95=6−25+95

=305−25+95=305−25+95

=30−2+95=375=30−2+95=375

b) (3135−47)(3135−47) x 87:287:2

=(3135−2035)=(3135−2035) x 87:287:2

=1135=1135 x 8

giúp mik với ạ!!!

Câu 2: B

Câu 3: B

Câu 4: A

giup toi  tui voi