\(X^2-2XY+Y^2+2X-2Y\)
\(\Leftrightarrow\left(X^2-2XY+Y^2\right)+\left(2X-2Y\right)\)
\(\Leftrightarrow\left(X-Y\right)^2+2\left(X-Y\right)\)
\(\Leftrightarrow\left(X-Y\right)\left(X-Y+2\right)\)
Tk mình nhé.
\(\left[x-y\right]^2+2\left[x-y\right]=x-y.\left[x-y+2\right]\)
x^2-2xy=y^2+2x-2y
(x-y)^2+.(2x-2y)
(x-y)^2+2(x-y)
(x-y)(x-y+2)