I can't really read what your question is asking. From the context, I am assuming this is f(x):
Is that correct?
Assuming it is, then since . So, for all , and for all , .
Also, for all real values of . So, you have a positive times a negative for all values of x where and you have a positive times a positive for all .
Do you know how to use integration by parts? What method are you using to find the area enclosed by the graph and the x-axis? Are you treating area below the x-axis as "negative" area?