For the function given below, find a formula for the Riemann sum obtained by dividing the interval [a,b] inton equal subintervals and using the right-hand endpoint for each . Then take a limit of this sum as n - to calculate the area under the curve over (a,b] f(x) 4x over the interval (1,5). Find a formula for the Riemann sum. S- The area under the curve over [1,5) is square units. (Simplify your answer.)