x= e^{ln x }
n= 1/u .... also u=1/n . ... mit u->0 wenn n->oo
n* ( x^{1/n} -1) ... -> .. [ e^{u * ln x } -1 ] / u
etwas verallgemeinert : sei u in R ->
lim_(u->0) { [ e^{u * ln x } -1 ] / u } ..... de l ' Hospital ->
lim_(u->0) { [ ln x * e^{u * ln x } ] / 1 } = [ ln x * e^{0 * ln x } ] / 1 = ln x