\(\Leftrightarrow\left(4x^2-20xy+25y^2\right)+3\left(x^2+10x+25\right)+\left(y^2+4y+4\right)=0\)
\(\Leftrightarrow\left(2x-5y\right)^2+3\left(x+5\right)^2+\left(y+2\right)^2=0\)
\(\Leftrightarrow\left\{{}\begin{matrix}2x-5y=0\\x+5=0\\y+2=0\end{matrix}\right.\) \(\Leftrightarrow\left(x;y\right)=\left(-5;-2\right)\)