Question

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Answer 1

\(7\dfrac{1}{2}+5\dfrac{3}{4}+2\dfrac{1}{2}+4\dfrac{1}{4}\\ =\left(7+5+2+4\right)+\left(\dfrac{1}{2}+\dfrac{3}{4}+\dfrac{1}{2}+\dfrac{1}{4}\right)\\ =18+2=20\)

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\(8\dfrac{3}{4}+4\dfrac{1}{5}-3\dfrac{3}{4}\\ =\left(8+4-3\right)+\left(\dfrac{3}{4}+\dfrac{1}{5}-\dfrac{3}{4}\right)\\ =9+\dfrac{1}{5}=9\dfrac{1}{5}\)

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\(15\dfrac{1}{3}x\dfrac{2}{7}+15\dfrac{1}{3}x\dfrac{5}{7}\\ =15\dfrac{1}{3}x\left(\dfrac{2}{7}+\dfrac{5}{7}\right)=15\dfrac{1}{3}x1\\ =15\dfrac{1}{3}\)

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\(3\dfrac{1}{2}:\dfrac{1}{2}-3\dfrac{1}{2}:\dfrac{1}{4}\\ =3\dfrac{1}{2}x2-3\dfrac{1}{2}x4=3\dfrac{1}{2}x\left(2-4\right)\\ =3\dfrac{1}{2}x\left(-2\right)=\dfrac{7}{2}x\left(-2\right)\\ =-7\)

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\(\left(\dfrac{3}{7}x\dfrac{11}{15}+\dfrac{3}{7}x\dfrac{4}{15}\right):\left(15+\dfrac{6}{11}-14\dfrac{6}{11}\right)\\ =\left(\dfrac{3}{7}x\left(\dfrac{11}{15}+\dfrac{4}{15}\right)\right):\left(15\dfrac{6}{11}-14\dfrac{6}{11}\right)\\ =\left(\dfrac{3}{7}x\dfrac{15}{15}\right):\left(\left(15-14\right)+\left(\dfrac{6}{11}-\dfrac{6}{11}\right)\right)\\ =\left(\dfrac{3}{7}x1\right):\left(1+0\right)=\dfrac{3}{7}:1=\dfrac{3}{7}\)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

nếu thấy nó để trống ở dưới dài quá là do khi kt ko thấy nó đủ nên làm vậy cho lòi hết ro á

Answer 2

`7 1/2 + 5 3/4 + 2 1/2 + 4 1/4`

`= ( 7 + 5 + 2 + 4) + (1/2 + 3/4 + 1/2 + 1/4)`

`= 18 + 2`

`= 20`

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`8 3/4 - 4 1/5 - 3 3/4`

`= ( 8 - 4 - 3) + ( 3/4 - 1/5 - 3/4)`

`= 1 + (-1)/5`

`= 4/5`

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`15 1/3 xx 2/7 + 15 1/3 xx 5/7`

`= 15 1/3 xx ( 2/7 + 5/7)`

`= 15 1/3 xx 7/7`

`= 15 1/3 xx 1`

`= 15 1/3`

`= 46/3`

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`3 1/2 : 1/2 - 3 1/2 : 1/4`

`= 3 1/2 xx 2 - 3 1/2 xx 4`

`= 3 1/2 xx (2 - 4)`

`= 3 1/2 xx (-2)`

`= 7/2 xx (-2)`

`= (-7)`

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`(3/7 xx 11/15 +3/7 xx 4/15) : ( 15 + 6/11 - 14 6/11)`

` = [ 3/7 xx ( 11/15 + 4/15)] : [ (15 - 14)  ( 6/11 - 6/11)]`

` = [ 3/7 xx 15/15] : [ 1 + 0)`

` = [ 3/7 xx 1] : 1`

`= 3/7 : 1`

`= 3/7`