10: The expression is of the type
ln(1 + e∞) − ∞ = ln(1 + ∞) − ∞ = ln(∞) − ∞ = ∞ − ∞.
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.