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The roots of the quadratic equation z^2 + bz + c = 0$ are -7 + 2i and -2i + 7. What is b+c?

 
 Sep 11, 2021
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   root 1     -7 + 2i       means   (x- (-7+2i))   is a factor  of the quadratic:   (x+7-2i)

          2                                    (x- (7 - 2i)    is a factor                               (x - 7+2i)

 

 

   ( I suspect the second root should be -7 - 2i)

 

(x+7-2i)(x-7+2i)      will be your quadratic ....but it will not be of the form    z^2 + bz + c = 0    

    if the second root is   (-2i - 7)    you will get the factor    (x+7+2i)

               then factor1 * factor2    would be      (x+7-2i)(x+7+2i)     and when multiplied out would be of the correct form to calculate b+c.....

 
 Sep 12, 2021

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