Three results for nding the area under the curve y= 2x x2 +1 , between x = 0 and x = 6, are shown below. The result found by dividing the interval into 6 subintervals and then adding up the areas of the inscribed rectangles is approximately 114.72. The result found by dividing the interval into 12 subintervals and then adding up the areas of the inscribed rectangles is approximately 131.59. The exact result found by evaluating the antiderivative at the bounds is approximately 149.37. Explain the differences between these results