\(\Leftrightarrow9x^2+9y^2+12xy+6x-6y+6=0\)
\(\Leftrightarrow\left(9x^2+4y^2+1+12xy+6x+4y\right)+5\left(y^2-2y+1\right)=0\)
\(\Leftrightarrow\left(3x+2y+1\right)^2+5\left(y-1\right)^2=0\)
\(\Leftrightarrow\left\{{}\begin{matrix}3x+2y+1=0\\y-1=0\end{matrix}\right.\) \(\Rightarrow\left\{{}\begin{matrix}x=-1\\y=1\end{matrix}\right.\)