Lim x→∞ (5x^3-4x+7)/(4e^(2x)-4x-1) L'Hospitals Rule!?

This meets L'Hospitals Rule of Inf/inf so I cant take the top and bottom derivative. When I do that I get (15x^2-4)/(8e^(2x)-4) now I don't know what to do from there. Help would be greatly appreciated. Thank you!