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1+2+3+....+50 b)1+2+3+...75 c)1+2+3+...101

Răspuns :

A=. 50x51:2 = 25 x 51 =1275

B)
= 75 x 78 :2= 75 x 39 = 2925

C= 101x102:2= 101 x 51 = 5151