x平方-2xy-3y平方+3x-5y+2
=(x²-2xy-3y²)+(2x-6y)+(x+y)+2
=(x-3y)(x+y)+2(x-3y)+(x+y)+2
=(x-3y)(x+y+2)+x+y+2
=(x-3y+1)(x+y+2)