> On 9 Mai, 02:48, Ralf Bader <ba...@nefkom.net> wrote: >> Virgil wrote: >> > WM <mueck...@rz.fh-augsburg.de> wrote: >> >> On 8 Mai, 21:56, Virgil <vir...@ligriv.com> wrote: .. >> >> If for every sequence (x_n) with limit x_0 the limit of the sequence >> >> of difference quotients >> >> (f(x_n) - f(x_0))/(x_n - x_0) exists and is the same in all cases, >> >> then df/dx is defined at x_0. >> >> > But that one sequence gives a limit does not guarantee that that >> > sequence need give the same result as any other sequence. > > Therfore I said "for every sequence (x_n) with limit x_0."
And x_0 is what, in this case? An infinite natural???