20: After substituting in the limit point you should find that the expression is of the type ∞ − ∞:

Note that it was crucial to check what kind of "1" is e⁰, since only then one can in the next step figure out 1/0. For n positive (which they are, they tend to infinity) one has 1/n > 0, so that's how one gets the "0⁺". Since e to a positive number is greater than 1 and we approach 0 from the positive side, the exponential approaches "1" from numbers that are greater, that is, from the right.

Now what to do with this limit? While the first term is under a root, getting rid of it would not improve the situation. One could try the universal trick for changing difference into ratio (see the box "indeterminate difference"), but it would be beastly. Far better choice is to try to make the difference into a fraction using some common denominator, since the second term is already in the form of a fraction.

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