x²-y²+2x-4y-3=(x²+2x+1)-(y²+4y+4)=(x+1)²-(y+2)²=[(x+1)-(y+2)][(x+1)+(y+2)]=(x-y-1)(x+y+3)
x^2-y^2+2x-4y-3 =(x^2+2x+1)-(y^2+4y+4) =(x+1)^2-(y+2)^2=[(x+1)-(y+2)][(x+1)+(y+2)] =(x-y-1)(x+y+3)
