SOLUTION: What are the other roots of {{{y=x^3-6x^2+13x-20}}} if one of its roots is 1+2i

SOLUTION: What are the other roots of {{{y=x^3-6x^2+13x-20}}} if one of its roots is 1+2i

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Question 252410: What are the other roots of if one of its roots is 1+2i
Answer by drk(1908) (Show Source): You can put this solution on YOUR website!
Since 1 + 2i is a root its conjugate 1 - 2i is also a root. Conjugates always travel in pairs. So [x-1+2i][x-1-2i] = X^2 -2x + 5 appears to be a root. By polynomial division, we get x-4.
SO, the three roots are X = 1+-2i, 4.
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