Concavity and critical numbers

I am attempting to study for a test, but I forgot how to do all the stuff from earlier in the chapter.

I am attempting to find the intervals where f is increasing and decreasing, min and max values and intervals of concavity and inflection points.

I have $f(x)={e}^{2x}+{e}^{-x}$. I know that I have to find the derivative, set to zero to find the critical numbers then test points then find the second derivative and do the same to find the concavity but I don't know how to get the derivative of this. Wolfram Alpha gives me a completely different number than what I get.

I am attempting to study for a test, but I forgot how to do all the stuff from earlier in the chapter.

I am attempting to find the intervals where f is increasing and decreasing, min and max values and intervals of concavity and inflection points.

I have $f(x)={e}^{2x}+{e}^{-x}$. I know that I have to find the derivative, set to zero to find the critical numbers then test points then find the second derivative and do the same to find the concavity but I don't know how to get the derivative of this. Wolfram Alpha gives me a completely different number than what I get.