Ta có:

\(x^2-2xy+2y^2-2x+6y+5=\left(x^2-xy+y^2\right)+y^2-2\left(x-y\right)+4y+5\)

\(=\left[\left(x-y\right)^2-2\left(x-y\right)+1\right]+\left(y^2+4y+4\right)\)

\(=\left(x-y-1\right)^2+\left(y+2\right)^2=0\)

\(\Rightarrow\hept{\begin{cases}x-y=1\\y=-2\end{cases}\Rightarrow\hept{\begin{cases}x=y+1=-1\\y=-2\end{cases}}}\)

\(x^2+xy-2012x-2013y-2014=0\)

\(\Leftrightarrow x\left(x+y\right)-2013x-2013y+x-2013-1=0\)

\(\Leftrightarrow x\left(x+y\right)-2013\left(x+y\right)+\left(x-2013\right)-1=0\)

\(\Leftrightarrow\left(x+y\right)\left(x-2013\right)+\left(x-2013\right)-1=0\)

\(\Leftrightarrow\left(x-2013\right)\left(x+y+1\right)=1\)

\(\Leftrightarrow\left(x-2013\right);\left(x+y+1\right)\in\left\{-1;1\right\}\)

\(\Leftrightarrow\left(x;y\right)\in\left\{\left(2012;-2014\right);\left(2014;-2014\right)\right\}\left(x;y\inℤ\right)\)

\(\sqrt{ }\)^{2₃₊₉₉₉₉}

\(x^2+xy-2012x-2013y-2014=0\)

\(\Rightarrow x\left(x+y\right)-2013\left(x+y\right)+\left(x-2013\right)-1=0\)

\(\Rightarrow\left(x-2013\right)\left(x+y+1\right)=1\)

Ta có bảng sau

Ngu quá nên kẻ thừa, thông cảm :)