Question

Find a degree 3 polynomial with real coefficients having zeros 4 and 4i and a lead coefficient of 1. Write P

Answer 1

Answer:

P(x)= x^3 - 4x^2 + 16x - 64

Step-by-step explanation:

First, let’s find all of the zeroes. If the question is asking for a degree 3 polynomial, than there has to be more than 2 zeroes. The complex conjugates theorem states that if a+bi is a zero, than a-bi has to be a zero as well. So if 4i is a zero, than -4i has to be a zero as well. By looking at the zeroes, you can write them as a linear factorization.

(x-4)(x+4i)(x-4i)

If you foil all of it, you will get x^3 - 4x^2 + 16x - 64.