Answer:
-15.96
Step-by-step explanation:
A conjugate is a binomial with the sign inside changed. So the conjugate of (1/5 + 4i) is (1/5 - 4i)
Set the original and the conjugate next to each other and F.O.I.L. Multiply the first numbers of each binomial, the 1/5 and the 1/5 to get 1/25. This is the "F."
Multiply the outer members, the 1/5 and the 4i to get - 60i. This is the "O."
Multiply the inner numbers ( the + 4i and the 1/5) to get + 60i. This is the "I."
Multiply the positive 4i and the negative 4i to get 16i squared
The positive 60i and the negative 60i cancel each other out.
The i squared changes into - 1. This makes the 16 negative.
Add 1/25 to - 16 to get - 15.96
