2x^2-5x+2y^2-5y-5xy-25
=2x^2-5xy+2y^2-5x-5y-25
=(2x-y)(x-2y)-5x-5y-25
=(2x-y)(x-2y)-10x+5y+5x-10y-25
=(2x-y)(x-2y)-5(2x-y)+5(x-2y)-25
=(2x-y+5)(x-2y-5)