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One root of a quadratic with real coefficients is 2 + i*3*sqrt(5).  Find the quadratic.

 Sep 18, 2020
 #1
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Imaginary roots come in + -  p airs           the other root is  2 - 3 sqrt5 i

 

(x - 2 - i 3 sqrt5)(x-2+i 3 sqrt 5 )    Multiply this all out to get:

 

=  x^2 -4x+49  

 Sep 18, 2020

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