`4/7 + 4=4/7+ 28/7 = 32/7`

=4 4/7 = 19/7

-58

toán thì viết tiếng việt chứ đừng viết tiếng anh

`17/6 +(5/9 -1/4)`

`= 17/6 + ( 20/36 -9/36)`

`= 17/6 + 11/36`

`= 102/36 + 11/36`

`= 113/36`

=17/6+(20/36-9/36)

=17/6+11/36

=102/36+11/36

=112/36=8/3

`4+1/2= 8/2 +1/2= 9/2`

`5/6+3=5/6+ 18/6 = 23/6`

`1+2/3= 3/3+2/3=5/3`

`3+4/5= 15/5 +4/5= 19/5`

`5+3/7= 35/7 + 3/7= 38/7`

`6/8+2=6/8+16/8 = 22/8=11/4`

`4 +1/2 = 8/2 +1/2 =9/2`

`5/6 +3 = 5/6 + 18/6 = 23/6`

`1+2/3 = 3/3 +2/3 =5/3`

`3 +4/5 = 15/5 + 4/5 = 19/5`

`5 +3/7 = 35/7 +3/7 = 38/7`

`6/8 +2 = 3/4 + 8/4 = 11/4`

\(\dfrac{181818}{212121}=\dfrac{181818:10101}{212121:10101}=\dfrac{18}{21}\)

\(\dfrac{18}{21}=\dfrac{18:3}{21:3}=\dfrac{6}{7}\)

Vậy \(\dfrac{181818}{212121}=\dfrac{6}{7}\) ta chọn C

help gấp 

cứu ;-;

a) \(\dfrac{3}{35}+\dfrac{7}{20}+\dfrac{32}{35}+\dfrac{13}{20}\)

Áp dụng tính chất giao hoán, kết hợp của phép cộng, ta được:

\(\left(\dfrac{3}{35}+\dfrac{32}{35}\right)+\left(\dfrac{7}{20}+\dfrac{13}{20}\right)\)

\(=1+1\)

\(=2\)

b) \(\dfrac{18\cdot15\cdot56}{42\cdot27\cdot25}=\dfrac{2\cdot3\cdot3\cdot5\cdot3\cdot4\cdot2\cdot7}{2\cdot3\cdot2\cdot2\cdot3\cdot9\cdot5\cdot5}\)

\(=\dfrac{2\cdot2\cdot3\cdot3\cdot3\cdot4\cdot5\cdot7}{2\cdot2\cdot2\cdot3\cdot3\cdot5\cdot5\cdot9}=\dfrac{3\cdot2\cdot2\cdot7}{2\cdot5\cdot9}=\dfrac{42}{45}\)

`x-10/3=7/18+3/5`

`=> x-10/3=89/90`

`=> x=89/90+10/3`

`=> x=389/90`

thanhk you:)

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