2x" - 4x + xy - y - 6y" + 2
= (2x" + xy - 6y") - 4x - y + 2
= (2x" + 4xy - 3xy - 6y") - 4x - y + 2
= [ 2x(x + 2y) - 3y(x + 2y) ] - 2x - 2x - 4y + 3y + 2
= (x + 2y)(2x - 3y) - 2x - 4y - 2x + 3y + 2
= (x + 2y)(2x - 3y) - 2(x + 2y) - (2x - 3y - 2)
= (x + 2y)(2x - 3y - 2) - (2x - 3y - 2)
= (x + 2y - 1)(2x - 3y - 2)