# How do you find a third degree polynomial given roots #-4# and #4i#?

##### 1 Answer

Dec 27, 2017

#### Explanation:

Since the question ask for a third degree polynomial, I am going to assume that you want a polynomial with real coefficients, with

Each zero

#f(x) = (x+4)(x-4i)(x+4i)#

#color(white)(f(x)) = (x+4)(x^2-(4i)^2)#

#color(white)(f(x)) = (x+4)(x^2+16)#

#color(white)(f(x)) = x^3+4x^2+16x+64#

So we can write a cubic equation:

#x^3+4x^2+16x+64 = 0# with the desired roots.