We need to find a polynomial function f(x) with degree 3 and zeros 2 and 2i, such that:
Since 2i is a zero, -2i is also a zero of this function. Thus, we have:
where a is a constant.
Expanding the expression on the right side, we obtain:
Now, using f(-1) = 30, we obtain:
Therefore, the function is:
Answer
