Wednesday, 28 October 2015

discrete mathematics - Proof by Induction: n!>2n+1 for all integers ngeq5.

I have to answer this question for my math class and am having a little trouble with it.



Use mathematical induction to prove that n!>2n+1 for all integers n5.




For the basis step: (n=5)



5!=120



25+1=26=64



So 120>64, which is true.



For the induction step, this is as far as I've gotten:




Prove that (n!>2n+1)((n+1)!>2(n+1)+1)



Assume n!>2(n+1)
Then (n+1)!=(n+1)n!



After this, I'm stuck. Any assistance would be appreciated.



Thanks!

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