`3/7x - 1 = 1/7x(3x-7)` Giải phương trình

Đáp án:

`3/7x - 1 = 1/7x ( 3x - 7 )`

`<=>` `3/7x - 1 = 3/7x^2 - x`

`<=>` `3/7x - 1 - 3/7x^2 + x = 0`

`<=>` `3/7x - 3/7x^2 - 1 + x = 0`

`<=>` `3/7x ( 1 - x ) - ( 1 - x ) = 0`

`<=>` `( 1 - x ) ( 3/7x - 1 ) = 0`

`<=>` \(\left[ \begin{array}{l}1 - x = 0\\\dfrac{3}{7}x - 1 = 0\end{array} \right.\) 

`<=>` \(\left[ \begin{array}{l}x = 1\\\dfrac{3}{7}x = 1\end{array} \right.\) 

`<=>` \(\left[ \begin{array}{l}x = 1\\x = \dfrac{7}{3}\end{array} \right.\) 

Vậy `:` `S = { 7/3 ; 1 }`.