What is conjugate root theorem (in your own words)

This is the actual definition: In mathematics, the complex conjugate root theorem states that if P is a polynomial in one variable with real coefficients, and a + bi is a root of P with a and b real numbers, then its complex conjugate a - bi is also a root of P.

go ahead and change it to fit to what you would say

In mathematics, the complex conjugate root theorem states that if P is a polynomial in one variable with real coefficients, and a + bi is a root of P with a and b real numbers, then its complex conjugate a - bi is also a root of P.