Hello.

Find the other two zeroes of P(z) if -2+i is a zero or p(z)=2z^3+9z^2+14z+5.

My attempt:

-2+i is a zero, so -2-i is also a zero.

P(z)=2z^3+9z^2+14z+5

.....=(z-[-2-i])(z-[-2-i])(z-z3)

.....=((z+2)^2+1)(z-z3)

.....=(z^2+4z+5)(z-z3)

5*-z3= -5z3 (I do NOT mean -15z here)

......5=-5z3

.....-1=z3

Two other Zeroes are -2-i , -1

However, the correct answer given in the book is

-2-i and -0.5

Thank you :)