SOLUTION: givn one zero, find all other zeros that can be either real or complex. p(x)=x^4-x^3+7x^2-9x-18 (3i is a zero)

Algebra ->  Polynomials-and-rational-expressions -> SOLUTION: givn one zero, find all other zeros that can be either real or complex. p(x)=x^4-x^3+7x^2-9x-18 (3i is a zero)      Log On


   

Question 236849: givn one zero, find all other zeros that can be either real or complex.
p(x)=x^4-x^3+7x^2-9x-18 (3i is a zero)
Answer by edjones(8007) About Me  (Show Source):
You can put this solution on YOUR website!
p(x)=x^4-x^3+7x^2-9x-18 (3i is a zero)
if x=3i then x=-3i the 2nd zero.
(x-3i)(x+3i)=0
x^2+9=0
(x^4-x^3+7x^2-9x-18)/(x^2+9)
=x^2-x-2 long division
x^2-x-2=0
(x-2)(x+1)=0
x=2, x=-1 the 3rd and 4th zeros.
.
Ed