Hello from MrBillDoesMath!
Answer:
x + 9 and (x + ( i - 7)) are factors
Discussion:
If f(x) has roots -9 and 7-i then
f(x) = g(x)(x - (-9)) (x - (7-i)) ( g(x) is a polynomial of degree less than f(x))
That is, x + 9 and (x + ( i - 7)) are factors of f(x)
BTW: if the coefficients of f(x) are real (not stated in the Question) then the conjugate of 7-i, i.e. 7 + i, is also be a root.
Thank you,
MrB
