Use nite approximation to estimate the area under the graph of f(x) = 4x2 and above the graph of f(x) = 0 from x0. = 0 to xn = 8 using .6 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