Answer:
2x^2 + 2y^2 + 2z^2
Explanation:
x^2+xy-yx+y^2 + y^2+yz-zy+z^2 + z^2+zx-xz+x^2
First step is to put all the same ones together
( FYI, xy and yx is the same thing, just like how
2 x 3 and 3 x 2 is the same thing) this time I'll bracket the groups to make it easier on the eyes
(x^2 +x^2) + (xy - xy) +( y^2 + y^2) + (yz - yz) +
(z^2 +z^2) + (zx - zx)
2x^2 + 2y^2 + 2z^2
All the others just cancel themselves out, for example, xy-xy
When anything minus themselves it will become 0