Multiply the conjugates.
-(13 - 9i)(13 + 9i)
A) 4
B) 22
C) 250
D) 88

Question

Quizplus · Accepted Answer

When multiplying the conjugates of a complex number, the resulting product is always a real number. To find the answer, we can use the difference of squares formula: (a + b)(a - b) = a^2 - b^2. In this case, a = 13 and b = 9i. So, (13 - 9i)(13 + 9i) can be written as (13)^2 - (9i)^2, which simplifies to 169 - 81i^2. Since i^2 = -1, we can simplify further to get 169 + 81 = 250. Therefore, the answer is choice C.

Multiply the Conjugates. -(13 - 9i)(13 + 9i)