Question 1209715
.
Let P(x) be a polynomial of the form
P(x) = 2x^3 + ax^2 - 23x + c,
such that 12 and 7 are roots of P(x). What is the third root?

For the polynomial in part (a), compute the ordered pair (a,c). 
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        The solution in the post by  @CPhill is  INCORRECT.


        It is incorrect,  since he mistakenly uses  1/2  instead of  12  in all his calculations through his post.