` 4 - x = 2.(x - 4)^2 `
` => -(x - 4) - 2(x - 4)^2 = 0 `
` => (x - 4)(-1 - 2x + 8) = 0 `
` => (x - 4)(7 - 2x) = 0 `
` => ` \(\left[ \begin{array}{l}x-4=0\\7-2x=0\end{array} \right.\)
` => ` \(\left[ \begin{array}{l}x=4\\2x=7\end{array} \right.\)
` => ` $\left[ \begin{array}{l}x=4\\x=\dfrac{7}{2}\end{array} \right.$
Vậy ` x = 4 ` hoặc ` x = 7/2 `
