1:

a: =8/7-5/88=669/616

b: \(=1+\dfrac{2}{9}\cdot\dfrac{3}{7}-\dfrac{10}{7}=1+\dfrac{2}{21}-\dfrac{10}{7}\)

\(=\dfrac{21+2-30}{21}=\dfrac{-7}{21}=\dfrac{-1}{3}\)

c: \(=\dfrac{11}{3}-\dfrac{6}{7}+4=\dfrac{77-18+84}{21}=\dfrac{143}{21}\)

Bài 2:

a: =>9/4-x=5/11*2=10/11

=>x=9/4-10/11=59/44

b: =>2/9:x=19/21

=>x=2/9:19/21=14/57

a, 4/9 +1/2 = 17/18

b, 3/8 + 1/2 = 7/8

c, 9/8 + 3/5 = 69/40

d, 5 - 3/4 = 17/4

a. 4/9 + 1/2 = 17/18

b. 3/8 + 1/2 = 7/8

c. 9/8 + 3/5 = 69/40

d. 5 - 3/4 = 17/4

a: \(=\dfrac{7\cdot5+3\cdot9}{45}\cdot\dfrac{2}{3}=\dfrac{62}{45}\cdot\dfrac{2}{3}=\dfrac{124}{135}\)

b: \(=\dfrac{6}{11}\cdot\dfrac{5}{7}=\dfrac{30}{77}\)

c: \(=\dfrac{7}{8}\cdot\dfrac{8-3}{9}=\dfrac{7}{8}\cdot\dfrac{5}{9}=\dfrac{35}{72}\)

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\(\text{#TNam}\)

`a, (7/9+3/5) \times 2/3`

`C1:`

`=62/45 \times 2/3`

`= 124/135`

`C2:`

`= 7/9 \times 2/3 + 3/5 \times 2/3`

`= 14/27 +2/5`

`= 124/135`

`b, `

`C1:`

`= 6/11 \times 5/7`

`=`30/77`

`C2:

`= 9/11 \times 5/7-3/11 \times 5/7`

`= 45/77 -15/77`

`= 30/77`

`c,`

`C1:`

`= 7/8 \times 5/9`

`=35/72`

`C2:`

`= 7/8 \times 8/9- 7/8 \times 1/3`

`= 7/9-7/24`

`=35/72`

Chọn A

a] 4/12 ; 5/12 ; 11/2 ; 1/4

b] 1 ; 9/12; 12/5 ; 11/3

c] 8/21; 6/11;8/7

d] 2/3 ;2/7 15/2

a]1/3  5/12     11/2       1/4

b]1      3/4         12/5         33/9

c]8/21      6/11        8/7

d]2/3        2/7          15/2

a.\(\dfrac{2}{3}\times\dfrac{4}{9}+\dfrac{2}{3}\times\dfrac{5}{9}=\dfrac{2}{3}\times\left(\dfrac{4}{9}+\dfrac{5}{9}\right)=\dfrac{2}{3}\times1=\dfrac{2}{3}\)

b.\(\dfrac{7}{5}\times\dfrac{3}{4}-\dfrac{1}{2}\times\dfrac{3}{4}=\dfrac{3}{4}\times\left(\dfrac{7}{5}-\dfrac{1}{2}\right)=\dfrac{3}{4}\times\dfrac{9}{10}=\dfrac{27}{40}\)

c.\(\left(\dfrac{5}{6}+\dfrac{5}{8}\right)\times\dfrac{2}{3}=\dfrac{35}{24}\times\dfrac{2}{3}=\dfrac{35}{36}\)

a) 2/3 x 4/9 + 2/3 x 5/9 

=2/3 x ( 4/9 + 5/9)

= 2/3 x 1

=  2/3

b, 7/5 x 3/4 - 1/2 x 3/4

= ( 7/5 - 1/2 ) x 3/4

=     9/10         x 3/4

=         21/40

c, ( 5/6 + 5/8 ) x 2/3       

 =      35/24 x 2/3

=       35/36