n=3; 2 and 5i are zeros; f(1)=-78 what is f(x)?

Question

what is f(x)=?

Answer 1

f(x)=k(x-2)(x+5i)(x-5i)     where k is a constant

f(x)=k(x-2)(x^2-5i^2)=k(x-2)(x^2+25)=k(x^3+25x-2x^2-50)

f(1)=k(1+25-2-50)

-78=k(-26)

26k=78

k=78/26=3

f(x)=3(x^3-2x^2+25x-50)