Primes

Find all primes p p , given that p + 11 p ( p + 1 ) ( p + 2 ) p + 11 \vert\ p(p+1)(p+2)

N o t e : Note: Give your answer as the sum of these primes


The answer is 116.

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1 solution

André Hucek
Sep 26, 2017

Let p = 11 p = 11 , which seems to satisfy the condition, else p p is disordered with p + 11 p + 11 . In the second case, p + 11 p ( p + 1 ) ( p + 2 ) p + 11\vert p(p+1)(p+2) if it also divides the product ( p + 1 ) ( p + 2 ) (p+1)(p+2) . Which = ( 10 ) ( 9 ) = (-10)(-9) in m o d p + 11 \mod{p + 11} , so it must be true that p + 11 90 p + 11\vert90 , so p 7 , 19 , 79 p\in {7, 19, 79}

Therefore 7 + 11 + 19 + 79 = 116 7 + 11 + 19 + 79 = \boxed{116}

Exactly!! Same!

Md Zuhair - 3 years, 8 months ago

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