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# STEP 2 watch

1. For Step paper 2 2002, im having trouble with question 3 when they ask u to deduce that no 2 fermat numbers have common factors greater than 1. i guess they're asking you to prove that their primes? some hints please!!
2. (Original post by blubber123)
For Step paper 2 2002, im having trouble with question 3 when they ask u to deduce that no 2 fermat numbers have common factors greater than 1. i guess they're asking you to prove that their primes? some hints please!!
They aren't primes. You are proving that they are coprime though. It is fairly obvious from the induction you have just proved. If something divides Fk then it divides F0F1F2...Fk-1 + 2
edit: lol I misread the question I think but w/e
3. (Original post by 13 1 20 8 42)
edit: lol I misread the question I think but w/e
Don't think so, what you say sounds fine. Proof by contradiction works very well here, but might be overkill for a deduce
4. (Original post by Zacken)
Don't think so, what you say sounds fine. Proof by contradiction works very well here, but might be overkill for a deduce
Yeah my reasoning was still right, I just hadn't actually read properly what numbers were being talked about, just kinda assumed they weren't prime.

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