分解因式(x+y)(x+y+2xy)+x^2y^2-1

分解因式(x+y)(x+y+2xy)+x^2y^2-1

原式=(x+y)^2+2xy(x+y)+(xy)^2-1
=(x+y+xy)^2-1
=(x+y+xy-1)(x+y+xy+1)
=(xy+x+y-1)(x+1)(y+1)