1. The problem statement, all variables and given/known data Find, using l'Hôpital's rule: lim x-> ∞ ((tan(ax)-atanx)/(sin(ax)-asinx)) Where a is a non constant greater than ± 1. 2. Relevant equations - 3. The attempt at a solution I can't work out anything from this point. I don't know how to change or factorize the expression (is there a possible way to separate the (ax) angle?