Proof: d/dx(ln x) = 1/x | Derivatives of common functions | Khan Academy
I think you misunderstood what he said. The two main ways (they are mathematically the same thing) of defining e are: e = lim n→ 0 (1+n)^(1/n) Now, let us define k as k = 1/n Let us replace n with 1/k (remember to convert what the limit is approaching) e ...