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Compute the sum of all integers a for which the polynomial x^2+ax+10a can be factored over the integers.

 Jan 21, 2021
 #1
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All the solutions are

a = 0: x^2 = x*x

a = 40: x^2 + 40x + 400 = (x + 20)(x + 20)

a = 45: x^2 + 45x + 450 = (x + 15)(x + 30)

a = 72: x^2 + 72x + 720 = (x + 12)(x + 60)

 

0 + 40 + 45 + 72 = 157

 Jan 21, 2021
 #2
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Good answer, but what about the negative numbers? I think you're missing some positive numbers as well. 

 Jan 22, 2021
edited by KitSoundwave  Jan 22, 2021

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