Question

(x-6)(x-3i)(x+3i) in standard form

Answer 1

(x-6)(x-3i)(x+3i)
leave the first term and first of all multiply next two terms by formula that is
(a+b)(a-b) = a^2 - b^2

Answer 2

(x-3i)(x+3i) = (x^2 - 9i^2)

(x-6)(x^2 - 9i^2) = x^2 - 9i^2(x-6) = x^2(x-6) - 9i^2(x-6) =
x^3 - 6x^2 - 9xi^2 + 54i^2 = x^3 - 6x^2 + 45i^2