You can
put this solution on YOUR website!Your polynomial has Real coefficients.
You are told that -5i is a "zero" of the polynomial
Therefore +5i must be a "zero" of the polynomial
Therefore (x-5i)(x+5i)=x^2+25 is a factor of the polynomial
Divide the polynomial by x^2+25 and you will get a quotient of x+3.
that means "-3" is also a zero of the polynomial.
You now have all three zeroes of the polynomial.
Cheers,
Stan H>