Multiply each complex number by its conjugate.

6i

36

Step-by-step explanation:

for a complex no. a+bi, the conjugate is a-bi

6i is 0+6i,

It's conjugate is 0-6i, or just - 6i

(6i) * (-6i)

-36i²

since i² = - 1,

-36i² = - 36 (-1) = + 36