x²-y²+5x+3y+4（x+y-2xy)(x+y-z)+(xy-1）²

x²-y²+5x+3y+4（x+y-2xy)(x+y-z)+(xy-1）²
x²-y²+5x+3y+4
（x+y-2xy)(x+y-z)+(xy-1）²

x²-y²+5x+3y+4（x+y-2xy)(x+y-z)+(xy-1）²
（1）原式
=(x+y)(x-y)+(5x+3y)+4
=(x+y)(x-y)+(4x+4y)+x-y+4
=(x+y)(x-y+4)+(x-y+4)
=(x-y+4)(x+y+1)




第二题那个z应该是2吧