Question

How do you multiply `(5 + 2i)(5 - 2i)`?

Answer 1

`25-4i^2`

Explanation:

It matters not if `i` is an imaginary number or not - the laws of algebra applies equally to all terms.
There is no difference between `(5+2i)(5-2i)` and `(5+2x)(5-2x)`.

Therefore, the answer is `25-4i^2`.