Giải phương trình: x^2-6x+2=0

`x^2-6x+2=0`

`<=>(x^2-6x+9)-7=0`

`<=>[x^2-2.x. 3+3^2]-(\sqrt{7})^2=0`

`<=>(x-3)^2-(\sqrt{7})^2=0`

`<=>(x-3-\sqrt{7})(x-3+\sqrt{7})=0`

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

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

`Vậy` `S={3+\sqrt{7};3-\sqrt{7}}`