Question

Giúp mình với ạ

Answer 1

`(x+y+z)^2 - (x+y-z)^2`

`= (x+y+z-x-y+z)(x+y+z+x+y-z)`

`= 2z . (2x + 2y)`

`= 4xz + 4yz`.

Answer 2

=(x+y+z-x-y+z)(x+y+z+x+y-z)

=(2x+2y)*2z

=4z(x+y)