Estimate the area under the graph of f(x) = x + 4 over the interval [0, 15] using 10 approximating rectangles and midpoints as sample points. M10 = Repeat the approximation using using 50 approximating rectangles. M50 == Repeat the approximation using using 100 approximating rectangles. M100 = Repeat the approximation using using 500 approximating rectangles. M500 = These consecutive approximations appear to be approaching what value? So, it appears that the following integral expression is valid: dx = Report any numerical answers accurate to 6 places. Remember not to round too early in your calculations.