\(\sqrt{ }\)^{2₃₊₉₉₉₉}

Ta có:

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

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

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

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

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

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

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

Ta có bảng sau

Ngu quá nên kẻ thừa, thông cảm :)

ta có: \(x^2+xy-2012x-2013y-2014=0.\)

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

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

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

mà x,y là các số nguyên nên

\(\orbr{\begin{cases}\hept{\begin{cases}x-2013=1\\x+y+1=1\end{cases}}\\\hept{\begin{cases}x-2013=-1\\x+y+1=-1\end{cases}}\end{cases}\Rightarrow\orbr{\begin{cases}\hept{\begin{cases}x=2014\\y=-2014\end{cases}}\\\hept{\begin{cases}x=2012\\y=-2012\end{cases}}\end{cases}}}\)

vậy (x;y)={ (2014;-2014) ;(2012;-2012)}

\(x^2+xy-2012x-2013y-2014=0\) \(0\)

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

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

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

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

Mà x,y lại là số nguyên 

Vậy \(\hept{\begin{cases}\left(x;y\right)=\left(2014;2014\right)\\\left(x;y\right)=\left(2012;2012\right)\end{cases}}\)

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