Question

Tìm x:

x\(^2\) - 12x + 12= 0

Answer 1

\(x^2-12x+12=0\)

\(\Rightarrow x^2-2.x.6+36-36+12=0\)

\(\Rightarrow\left(x-6\right)^2-24=0\)

\(\Rightarrow\left(x-6\right)^2=24\)

\(\Rightarrow\left(x-6\right)^2=\left(\pm2\sqrt{6}\right)^2\)

\(\Rightarrow\left[{}\begin{matrix}x-6=2\sqrt{6}\\x-6=-2\sqrt{6}\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}x=2\sqrt{6}+6\\x=6-2\sqrt{6}\end{matrix}\right.\)

Vậy \(x=2\sqrt{6}+6\) hoặc \(x=6-2\sqrt{6}\)