17: The expression is of the type
We used the fact that "exponentials dominate powers" to handle the difference of infinities in the logarithm. However, such considerations do not help with the main difference, since the two infinities are of the same kind (check). This is not a difference of roots, so that trick is out of the question. 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 change the difference into one expression using some algebra.