jimmy_boots wrote:I follow the L'Hopital's Rule method of solving this problem, but where did you get the "

" from?

This is a given identity thinger I should be familiar with? I haven't come across it, please let me know the deal.

This is just one of

many ways of

representing . It would be unreasonable to learn them

all by heart, but a familiarisation with their general forms may alert you to the possibility of

hiding in a particular problem. Learning a few of the simpler ones, like this, may prove useful (and save a lot of time).

In fact, by using the

more general version of this representation of

, the second solution can be simplified further:

Q. Find

Since

,

Therefore, .

Thinking about where this question originally came from, Temple University's 'Calculus on the Web' site, and the simplicity of the other 22 questions leading up to this one, I would imagine that the question may be testing for knowledge of this very representation of

.

DAiv