f = { s i n a x k 2 k + 1 , a > 0 0 , a = 0 t g e | a x | e k , a < 0 {\displaystyle f={\begin{cases}sin{\frac {ax^{\sqrt {k}}}{2^{k+1}}},a>0\\0,a=0\\tg{\frac {e^{|ax|}}{e{\sqrt {k}}}},a<0\end{cases}}}
