Write answer as a + bi

Question

Simplify and write answer as a + bi

a. (2 + 5i) + (-2 - 4i)

b. (6 + 8i) (3 - 3i)

Answer 1

Adding complex numbers: Simply add the real terms to get the real portion and add the imaginary terms to get the imaginary portion of the sum:

Example:

3 + 5i + 4 - 2i = 7 + 3i

To multiply: "cross multiply"--just as you would with a combination of term with unknwowns.

Example:

(2 + i) * (3 - i) =

6 - 2i + 3i - i²

i² = -1, so we have:

6 - 2i + 3i + 1 = 7 + i