Perform the desired operation. Write the answer in the form a + bi.
-$$( 6 + 7 i ) ( 6 - 7 i )$$
A) $- 13$
B) $36 - 49 i ^ { 2 }$
C) 85
D) $36 - 49 \mathrm { i }$

Question

Quizplus · Accepted Answer

To solve $(6 + 7i)(6 - 7i)$, use the formula for multiplying complex numbers: $a^2 - b^2$, where $a = 6$ and $b = 7i$. Thus, $36 - (7i)^2 = 36 - (-49) = 36 + 49 = 85$. Note that $i^2 = -1$.

Perform the Desired Operation (6+7i)(6−7i)( 6 + 7 i ) ( 6 - 7 i )(6+7i)(6−7i)

Perform the Desired Operation $( 6 + 7 i ) ( 6 - 7 i )$