\(2x^2+4y^2+4xy-4x+4=0\)
\(\Leftrightarrow\left(x^2+4xy+4y^2\right)+\left(x^2-4x+4\right)=0\)
\(\Leftrightarrow\left(x+2y\right)^2+\left(x-2\right)^2=0\)
\(\Rightarrow x-2y=0\) và \(x-2=0\)
\(\Rightarrow x=2\)
\(\Rightarrow2+2y=0\Rightarrow y=-1\)
Vậy \(x=2\) và \(y=-1\)
\(\Leftrightarrow\left(x^2+4y^2+4xy\right)+\left(x^2-4x+4\right)=0\)
\(\Leftrightarrow\left(x+2y\right)^2+\left(x-2\right)^2=0\)
\(\Leftrightarrow.....\)