Question

这个题怎么做，快快快，急用，谢谢，感谢。

这个题怎么做，快快快，急用，谢谢，感谢。谢谢啦。

Answer 1

追答

Answer 2

(x+2y-z)(x-2y-z)-(x+y-z)²
=[(x-z)+2y][(x-z)-2y]-(x+y-z)²
=(x-z)²-(2y)²-(x+y-z)²
=[(x-z)²-(x+y-z)²]-4y²
=(x-z+x+y-z)(x-z-x-y+z)-4y²
=(2x+y-2z)(-y)-4y²
=2yz-2xy-y²-4y²
=2yz-2xy-5y²

Answer 3

(x+2y-z)(x-2y-z)-(x+y-z)^2
=[(x+y-z)+y]. [(x+y-z)-3y] -(x+y-z)^2
=(x+y-z)^2 - 2y(x+y-z) -3y^2 -(x+y-z)^2
=- 2y(x+y-z) -3y^2
=-2xy -5y^2 +2yz

Answer 4

-2y(x+y-z)