4x^2 - 7x + 3 = 0 giúp mình với

#andy

\[\begin{array}{l}
4{x^2} - 7x + 3 = 0\\
 \Leftrightarrow 4{x^2} - 3x - 4x + 3 = 0\\
 \Leftrightarrow 4x(x - 1) - 3(x - 1) = 0\\
 \Leftrightarrow (x - 1)(4x - 3) = 0\\
 \Leftrightarrow \left[ \begin{array}{l}
x - 1 = 0\\
4x - 3 = 0
\end{array} \right.\\
 \Leftrightarrow \left[ \begin{array}{l}
x = 1\\
x = \dfrac{3}{4}
\end{array} \right.\\
 \Rightarrow S = \left\{ {1;\dfrac{3}{4}} \right\}
\end{array}\]

`4x^{2} - 7x + 3 = 0`

`=> 4x^{2} - 4x - 3x + 3 = 0`

`=> (4x^{2} - 4x) - (3x - 3) = 0`

`=> 4x(x - 1) - 3(x - 1) = 0`

`=> (4x - 3)(x - 1) = 0`

`=>`\(\left[ \begin{array}{l}4x - 3 = 0\\x - 1 = 0\end{array} \right.\) 

`=>`\(\left[ \begin{array}{l}4x=3\\x=1\end{array} \right.\) 

`=>`\(\left[ \begin{array}{l}x=3/4\\x=1\end{array} \right.\) 

Vậy `x ∈ { 3/4 ; 1 }`