2. Sendo x ∈ (2, 5, 7, 10, 12, 13, 15), determine:



∑7i=1xi
∑i=17xi





∑4i=1xi
∑i=14xi





∑7i=3xi
∑i=37xi







∑6i=4xi
∑i=46xi







3. Sendo x ∈ (0, 1, 1, 2, 3, 5, k, 13, 21) determine k e calcule:



∑9i=1xi
∑i=19xi