Which answer could be the result of two complex conjugates being multiplied together?(1 point)

Question

Responses

16i
16 i

9−9i
9 minus 9 i

25+4i
25 plus 4 i

20

Answer 1

The result of multiplying two complex conjugates is always a real number. When two complex conjugates, let's say \( a + bi \) and \( a - bi \), are multiplied together, the result is given by:

\[ (a + bi)(a - bi) = a^2 + b^2 \]

Since \( a^2 + b^2 \) is a sum of squares, it is always a non-negative real number.

From the options provided, the only choice that is a real number is:

20

So the answer is 20.