Did the question come with any answer choices to choose from? Since it’s specified as being a quadratic you know the general form should be
f(x) = ax^2 + bx + c
Then you can use other criteria given in the question to narrow it down further. For example, you would be looking for a function that meets the criteria where it crosses the x axis at x = -2 and x = 1 since it says that the roller coaster dips below the support bar in between those points. That also means that in between x = -2 and x = 1 the function would need to have a negative value.
I hope that helps get you moving in the right direction on this one! :)