Answer:
The remaining zeros are -7i, 4
Explanations:
Given the polynomial function:

Group the functions:

Factor out the common term in both parenthesis

Get the zeros of the function by making f(x) = 0

Equate both factors to zero;
![\begin{gathered} x^2+49=0 \\ x^2=-49 \\ x=\pm\sqrt[]{-49} \\ x=\pm\sqrt[]{49}*\sqrt[]{-1} \\ x=\pm7i \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/5raso9160qccjia457b8238amht05aer3x.png)
For the other factor (x-4) = 0

Given one of the zeros as 7i, the other zeros of the function will be -7i and 4