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Grade 12Algebra

suppose a,b and n are positive integers, all greater than 1. if a^n + b^n is prime, what can you say about n?

A) integer must be 2

B)integer need not be 2, but must be a power of 2

C)integer need not be a power of 2, but must be even

D)none of the above

Profile image of mihir mehan
16 Years agoGrade 12
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1 Answer

Profile image of Nehal Wani
16 Years ago

22+42=20  which is not a prime. Therefore (a) eliminated.

2 is also even. Therefore (c) eliminated.

34+54=706 which is not prime. Therefore option (b) eliminated.

Hence the correct option is (d)