4. Determine the nth derivative: 

restart;  

f := proc (x) options operator, arrow, function_assign; `^`(a, x) end proc;  

f := proc (x) options operator, arrow; `^`(a, x) end proc; (6.4.1)
 

diff(f(x), ('`$`')(x, n));  

`*`(`^`(a, x), `*`(`^`(ln(a), n))); (6.4.2)
 

(D[('`$`')(1, n)](f))(x);  

`*`(`^`(a, x), `*`(`^`(ln(a), n))); (6.4.3)