- #1

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^{1/u}

So, I used the chain rule and figured out that

f '(u) = (-u

^{-2}) e

^{1/u}

My question is, why do you have to use the chain rule?

I know that if f(x) = e

^{x}

then f '(x) = e

^{x}

Why can't I pretend that 1/u is x and then say that

f '(x) = e

^{x}= e

^{1/u}

In other words, does the exponent always have to be "x" only, for f '(x) = e

^{x}to work?