Question

tính giá trị biểu thức

8/15 : 2/11 + 7/15 : 2/11

2/3 + 5/2 - 3/4

4/5 -  1/2 + 1/3

Answer 1

\(\dfrac{8}{15}\times\dfrac{11}{2}+\dfrac{7}{15}\times\dfrac{11}{2}=\dfrac{11}{2}\left(\dfrac{8}{15}+\dfrac{7}{15}\right)=\dfrac{11}{2}\times\dfrac{15}{15}=\dfrac{11}{2}\times1=\dfrac{11}{2}\)

\(\dfrac{8}{12}+\dfrac{30}{12}-\dfrac{9}{12}=\dfrac{19}{12}\)

\(\dfrac{24}{30}-\dfrac{15}{30}+\dfrac{10}{30}=\dfrac{19}{30}\)

Answer 2

`8 / 15 : 2 / 11 + 7 / 15 : 2 / 11`

`= ( 8 / 15 + 7 / 15 ) : 2 / 11`

`= 15 / 15 xx 11 / 2`

`= 1 xx 11 / 2 = 11 / 2`

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`2 / 3 + 5 / 2 - 3 / 4`

`= 8 / 12 + 30 / 12 - 9 / 12`

`= 29 / 12`

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`4 / 5 - 1 / 2 + 1 / 3`

`= 24 / 30 - 15 / 30 + 10 / 30`

`= 19 / 30`

Answer 3

a. = 8/15 x 11/2 + 7/15 x 11/2

= (8/15 + 7/15) x 11/2

= 1 x 11/2

= 11/2

b. = 2/3 + 10/4 - 3/4

= 2/3 + 7/4

= 8/12 + 21/12

= 29/12

c. = 8/10 - 5/10 + 1/3

= 3/10 + 1/3

= 9/30 + 10/30

= 19/30