Algebra
posted by Lynn on .
I am trying to find the real coefficients of the given roots. Did I do this right?
3,9,3+2i
(x3)(x+9)[x(3+2i)][x(32i)]=0
(x3)(x+0)[(x3)+2i][(x3)2i]=0
(x3)(x+9)[(x3)^22i^2]=0
(x3)(x+9)(x^26x8)=0
(x^471x^2+114x+216)=0
answer x^471x^2+114x+216=0

Hmm.. I never done this before but I think you are right for the most part. You made a mistake on (x3)(x+9)(x^26x8) = 0. (x3)^2  2i^2 does not expand to x^26x8.
x3)^2  2i^2
x^2  6x + 9 + 2
x^2  6x + 11