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The polynomial p(x) = x^2+ax+b has distinct roots 2a and b. Find a+b.

 Oct 31, 2019
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Set the two givens =

(x-2a)(x-b) = x^2 +ax+b

x^2 -2ax-bx+2ab = x^2+ax+b

-2ax-bx+2ab = ax+b

 

so    -2ax-bx = ax      and   2ab = b  

        -2a-b = a          and    2 ab = b

         -b = 3a             and   2a = 1

         -b = 3a             and  a = 1/2

        -b = 3/2

         b = -3/2                  You can add them together...I hope !   cheeky

 Oct 31, 2019

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