Question

Three of the zeros of a fourth degree polynomial equation are 1, −1, 2i. Write the equation for the function if f(0) = 8.

Answer 1

you know what the other zero is?

Answer 2

A fourth degree poly has five terms. The fifth is given by f(0)=8. Hint: One factor of the poly is (x-1). What are the other three factors?

Answer 3

the factors are (x+1)(x-1)(x+2i)(x-2i) but i'm not sure what to do with f(0)=8

Answer 4

An example would work here,
\[f(x)=K(x-a)(x-b)(x-c)(x-d)\] You know a,b,c,d but you don't know K. So you calculate,
\[f(0)=(-a)(-b)(-c)(-d)\] And you can find the answer from this point.