Question

When you multiply (3+6i)(3+7i) you get an answer of the form a+bi. Find a.

Answer 1

(3 + 6i)(3 + 7i)

FOIL: First, Outside, Inside, and Last

3 x 3 = 9

3 x 7i = 21i

6i x 3 = 18i

6i x 71= 42i

9 + 21I + 18I + 42I = 9 + 81I

a = 9

B = 81I