First, determine what the integral is for :

Did you get that? Note that I used a lower-caseto denote the original function, and capitalfto denote the integral. Next, evaluateFat the point x=4, and subtract the value at x = 1:F(x)

Note that the constantcancels out. Since the constant of integration always cancels when evaluating definite integrals, most people simply don't bother including it in their work, but I think it's good practice to not forget about it. Hope this helps!C