Question

How you do multiply complex numbers ? Example : (9 - 4i) (8 + 6i)

Answer 1

You multiply them just as you would multiply any normal polynomials, except there is a special rule. Since we know that i = √-1, the rule is that i² = -1. So, let's multiply:

$(9-4i)(8+6i) = 72+54i-32i-24i^2$

Let's simplify this:

$72+22i+(-24*-1)$

$72+22i+24 = 96+22i$

Therefore, your answer is 96 + 22i.