X Points: 0 Use finite approximation to estimate the area under the graph of f(x) = 4x and above the graph of f(x) = 0 from Xo = 0 to X, = 8 using i) a lower sum with two rectangles of equal width. ii) a lower sum with four rectangles of equal width. iii) an upper sum with two rectangles of equal width. iv) an upper sum with four rectangles of equal width. . . . The estimated area using a lower sum with two rectangles of equal width is square units. (Simplify your answer. Type an integer or a decimal.)