Question

simplify: (x+y+z) the whole square + (x+y-z) the whole square

Answer 1

(x+y+z)²+(x+y-z)²
= x²+y²+z²+2xy+2yz+2zx+x²+y²+z²+2xy-2yz-2zx
=2x²+2y²+2z²+4xy

Answer 2

Answer:

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

=2x+2y+2z+4xy+4yz+4zx