X³y² - xy -x³ +x =x( x²y² -x² -y +1)= x((x²y² -x²) - (y -1) =x(x²(y² -1) -(y-1)) =
x(x²(y -1)(y+1) -(y-1)) =x(y -1)(x²(y+1) -1)) =x(y-1)(x²y +x² -1).
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или немного иначе : x³y² - xy -x³ +x =(x³y² -x³) -(xy -x) =x³(y² -1) -x(y-1)=
=x³(y -1)(y+1)-x(y-1) =x(y-1)(x²(y+1) -1) = x(y-1)(x²y +x² -1).