Question

Using the given zero, find one other zero of f(x). Explain the process you used to find your solution. If2+i is a zero of f(x)=x^3+x^2-15x+25, find the other zeroes.

Answer 1

Real Coefficients (1, 1, -15, 25) suggest that 2-i had better be in there, as well.

Answer 2

if 2 +i is solution then 2-i will be also
let 3rd root is p
sum of roots = -1
(2 +i)+(2 -i) +p = -1
p = -5

so roots are
2 +i
2 -i
-5

Answer 3

complex roots always found in conjugate

Answer 4

...IF the coefficients are Real.