Multiply. Write your answer in a +bi form.
-$(7-4 \mathrm{i})(9+4 \mathrm{i})$
A) $79-8 \mathrm{i}$
B) $47-64 \mathrm{i}$
C) $-16 i^{2}-8 i+63$
D) $79+8 \mathrm{i}$

Question

Quizplus · Accepted Answer

To multiply complex numbers $(7-4i)(9+4i)$, use the distributive property: $7*9 + 7*4i - 4i*9 - 4i*4i = 63 + 28i - 36i - 16(-1) = 63 - 8i + 16 = 79 - 8i$, since $i^2 = -1$.

Multiply Write Your Answer in a +Bi Form (7−4i)(9+4i)(7-4 \mathrm{i})(9+4 \mathrm{i})(7−4i)(9+4i)

Multiply Write Your Answer in a +Bi Form $(7-4 \mathrm{i})(9+4 \mathrm{i})$