If x,y,zx, y, zx,y,z are in AP, then x2+8yz+z2x^2 + 8yz + z^2x2+8yz+z2 is equal to which of the following?
(x+z)2(x+z)^2(x+z)2
2(x+z)22(x+z)^22(x+z)2
(x−z)2(x-z)^2(x−z)2
4y24y^24y2