1-ый вариант
xy^2-by^2-ax+ab+y^2-a= y^2( x-b ) -a( x-b ) + y^2 -a=
( x-b )*( y^2 -a) + y^2 -a= ( y^2-a )*( x -b + 1 )
2-ой вариант
xy^2-ay^2-bx+ab+y^2-b= y^2( x-a ) -b( x-a ) + y^2 -b=
( x-a )*( y^2 -b) + y^2 -b= ( y^2-b )*( x -a + 1 )
3-ий вариант
xy^3-by^3-ax+ab-a+y^3= y^3( x-b ) -a( x-b ) -a+y^3=
( x-b )*( y^3 -a) -a+y^3= ( y^3-a )*( x -b + 1 )