# Math Help - Find units in Z[i]

1. ## Find units in Z[i]

Show that the only units in Z[i] are +1, -1, +i , -i.

2. If $a$ is a unit then $N(a) = 1$ if $a=x+iy$ then $N(a) = x^2+y^2$ we need that $x^2+y^2 = 1$