The limit is , not

There are many ways to go about it.

Let

Then you get:

Rewrite as:

The inside limit is a 'famous' one which equals -1/2, which easily derived using L'Hopital. You can do it without, but it's easier with the ol' Hospital rule

So, we have:

You wouldn't have to make the sub:

Start out with:

Now, use L'Hopital and get:

I hope you can read that. Sure is tiny. I have tried to make it bigger to no avail.