If z=x+iyz = x+iyz=x+iy, what is z⋅zˉz \cdot \bar{z}z⋅zˉ?
x2−y2x^2 - y^2x2−y2
x2+y2x^2 + y^2x2+y2
2x2x2x
∣z∣2|z|^2∣z∣2