Răspuns :
S = 12 + 13 + 14 + ...... + 75
→ stabilim cati termeni are suma, cu ratia = 1
75 - 12 + 1 = 63 + 1 = 64 termeni are suma
S = 64 x ( 12 + 75 ) / 2
S = 32 x 87
S = 2 784
S = 12 + 13 + 14 + ...... + 75
→ stabilim cati termeni are suma, cu ratia = 1
75 - 12 + 1 = 63 + 1 = 64 termeni are suma
S = 64 x ( 12 + 75 ) / 2
S = 32 x 87
S = 2 784