Use finite approximation to estimate the area under the graph of f(x) = 2x and above the graph of f(x) = 0 from x = 0 to x = 4 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 (Simplify your answer. Type an integer or a decimal.) square units. The estimated area using a lower sum with four rectangles of equal width is (Simplify your answer. Type an integer or a decimal.) square units. The estimated area using an upper sum with two rectangles of equal width is (Simplify your answer. Type an integer or a decimal.) square units. The estimated area using an upper sum with four rectangles of equal width is (Simplify your answer. Type an integer or a decimal.) square units.