For z=3+-2i, find z·conjugate(z).
Note
For a complex number z = a + bi, multiplying by its conjugate gives z·conjugate(z) = a² + b². This is the square of the modulus, so it is always non-negative. Here a = 3 and b = -2. Therefore z·conjugate(z) = (3)² + (-2)² = 9 + 4 = 13. So the correct answer is 13.
