Bilde erst mal die Ableitungen
f ' (x) = e x/a / a f ' ' (x) = e x/a / a^2 f ' ' ' (x) = e x/a / a^3
also f '(a) = e/a f ' ' (a) = e/a^2 etc
also Tylorreihe
f(x) = f(a) + f '(a) * (x-a) + f ' ' (a) / 2 ! * ( x- a) ^2 .......
= e + (e/a) * (x-a) + e/(2 ! * a^2 )* ( x- a) ^2 + e / ( 3 ! * a^3 ) * ( x-a) ^3 + .............