b)
Un = ∑ (k = 1 bis n) (2/n·(2 - (0 + k·(2/n)))) = 2 - 2/n
On = ∑ (k = 0 bis n - 1) (2/n·(2 - (0 + k·(2/n)))) = 2 + 2/n
d)
Un = ∑ (x = 0 bis n - 1) (1/n·(2·(0 + k·1/n)^2 + (0 + k·1/n))) = (7·n^2 - 9·n + 2)/(6·n^2)
On = ∑ (k = 1 bis n) (1/n·(2·(0 + k·1/n)^2 + (0 + k·1/n))) = (7·n^2 + 9·n + 2)/(6·n^2)