find derivative of $e^{3\sqrt{x}}$ using chain rule. im asked to find the derivative of this function using the chain rule.
$$e^{3\sqrt{x}}$$
here are my steps. 
step 1 -  identify the inner and outer functions. therefore I identified outer function as 
$e^x$ inner function as $3\sqrt{x}$
step 2-  i used derivative of outer function with respect to  inner times the derivative of inner function.  so the answer as i see it should be 
$$e(3\sqrt{x})\left(\frac{3}{2}x^{-1/2}\right) $$
however the answer is $$e^{3\sqrt{x}}\left(\frac{3}{2}x^{-1/2}\right)$$
what I'm missing? I know the derivative of $e^x = e^x$ is that were i'm going wrong?
Thanks in advance for any explanation clarification you guys can offer.
Miguel 

For the exponential function, $$\frac{d}{dx}\left(e^{f(x)}\right) = e^{f(x)}f'(x).$$
Here, $e^{f(x)} = e^{3\sqrt x}$, so $f(x) = 3\sqrt x = 3x^{1/2}$. So then we must have $$\frac{d}{dx}\left(e^{3\sqrt{x}}\right) = e^{3\sqrt{x}}\left(\frac{3}{2}x^{-1/2}\right) = \frac{3e^{3\sqrt x}}{2\sqrt x}$$

As per comments: Yes, $e^x$ is unique in comparison to $x^n$, in many ways, including the fact that the first is a very distinguished constant raised to a variable power whereas the second is a variable raised to a constant. So the power rule does not apply to $e^x$, nor does it apply to any constant raised to a variable. And with the unique constant $e$:  recall, $\;\frac{d}{dx}(e^x) = e^x$.
