It's been a while for me, but as I recall, with a quadratic, you have to restrict the values of x in which you're interested. You are interested in values of x close to 4. Well, then, suppose that 3<x<5. Can you now put a bound on the factor 2x+5? You know that x-4 will get small, because x is going to 4. You just need a bound on the other term. Perhaps you can continue from there?