What is the third degree polynomial function with real coefficients of 1 and 4i as zeros

Question

What is the third degree polynomial function with real coefficients of 1 and 4i as zeros

Answer 1

(x-1)(x-4i)(x+4i)=0  

(Complex roots come in pairs: if 4i is root then -4i is a root  as well)

(x-1)(x²+16)=0

x³-x²+16x-16=0