Question

Factorise x²+y²+2(xy+xz+yz)

Answer 1

X²+y²+2(xy-yz-zx)
x²+y²+2xy-2yz-2zx
(x²+y²+2xy)-(2yz+2zx)
(x+y)²-2z(y+x). (x²+y²+2xy = (x+y)² )
taking (x+y) common 

(x+y)(x+y-2z)
hope this helps

Answer 2

So the answer is

(x+y+2z) (x+y)