which equals (3 + 2i)(3 - 2i)?\na. 9 - 4i\nb. 9 + 4i\nc. 6 - 4i\nd. 5\ne. 13

Answer:

E. 13

Explanation:

Step1: Use FOIL method

$(3 + 2i)(3 - 2i)=3\times3+3\times(- 2i)+2i\times3+2i\times(-2i)$

Step2: Simplify each term

$=9-6i + 6i-4i^{2}$

Step3: Recall $i^{2}=-1$

$=9-4\times(-1)$

Step4: Calculate the result

$=9 + 4=13$