Question

Evaluate x²-6x when x=3-i.

Answer 1

10

Explanation:

We are going to substitute x = 3 - i into the expression x² - 6x

* Remember than i² = (√-1)² = -1. so when we multiply and get i² we're going to transform it into -1.*

⇒
`x^2-6x = (3 - i)^2 - 6 (3-i) = 9 - 6i+i^2 -18+6i\\=9 - 6i-1-18+6i\\=-10`

Thus, x² - 6x = 10 when x = 3-i