OK, I think may have figured this out.
I am not very good at this, here it is.
Prove: 2n-1<= n! for n >= 1
If we assume that P(k): 2k-1 <= n! for some integer k and k >= 1
then need to prove that 2k <= (k+1)!
therefore 2k=2*2k-1<=2k! <= (k+1)k! = (k+1)!
I think this is it, but I'm not sure.