x : 1/3 = 1/2 +1/3

=>x:1/3=5/6

=>x=5/6 x 1/3

=>x=5/18

(x:2/3):2/5=7/10

=>x:2/3=7/10 x 2/5 

=>x:2/3=7/25

=>x=7/25x2/3

=>x=14/75

CHÚC BẠN HỌC TỐT

cảm ơn bn nha!

cái này vừa gửi rồi mà:D

cách làm đấy cô ko cho >:(

1) \(x:\dfrac{1}{3}=\dfrac{1}{2}+\dfrac{1}{3}\)

\(\Rightarrow3\times x=\dfrac{5}{6}\Rightarrow x=\dfrac{5}{18}\)

2) \(\left(x:\dfrac{2}{3}\right):\dfrac{2}{5}=\dfrac{7}{10}\)

\(\Rightarrow\dfrac{3}{2}\times x=\dfrac{7}{10}\times\dfrac{2}{5}=\dfrac{7}{25}\)

\(\Rightarrow x=\dfrac{7}{25}:\dfrac{3}{2}=\dfrac{14}{75}\)

em cảm ơn 

\(x-\dfrac{1}{4}=\dfrac{-21}{10}\)

\(x=\dfrac{-21}{10}+\dfrac{1}{4}\)

\(x=\dfrac{-42}{20}+\dfrac{5}{20}=\dfrac{-37}{20}\)

x = 22 x 7/11

x = 14

3/2 x X = 11/2 - 7/4

3/2 x X = 22/7

X = 22/7 : 3/2

X = 44/21

Nhanh qá='))

x = 4

giải rõ ràng dc ko bn

x^3+1=9

x^3=8

x^3=2^3

=>x=2

=>x³=8

hay x=2

\(X:\dfrac{3}{9}=\dfrac{7}{8}\)

\(X=\dfrac{7}{8}\times\dfrac{3}{9}\)

\(X=\dfrac{21}{72}\)

\(\left(X-21\times13\right):11=30\)

\(X-273=330\)

\(X=603\)

`x:3/9=7/8`

`x=7/8xx3/9`

`x=7/24`

`-------------`

`(x-21xx13):11=30`

`(x-273):11=30`

`x-273=30xx11`

`x-273=330`

`x=330-273`

`x=57`

\(\Leftrightarrow x^3+2x^2-3x-x^3-3x^2=-4\)

\(\Leftrightarrow x^2+3x-4=0\)

=>(x+4)(x-1)=0

=>x=-4 hoặc x=1