Question

find the polynomial with zeros at (-1,4) and -3

Answer 1

You know that if a is a zero of a given polynomial, then the polynomial is divisible by (x-a), that is it can be written in the form (x-a)*[something]
Since you need it to have -1, 4 and -3 as zeros, the easiest way to get it would be to multiply the three (x-a) terms together. Your polynomial becomes
\[P(x)=[x-(-1)]*(x-4)*[x-(-3)]\]

Answer 2

It was actually (1-4i) and -3