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Calculati urmatoarele sume:

a) 1+2+3+.......+500
b)1+2+3+........+124
Va rog!


Răspuns :

a). =(500x501):2=250.500:2=125.250

b). =(124x125):2=15.500:2=7.750

a)[(500+1)×500]÷2=(501×500)÷2=250 500÷2=125 250

b) [(1+124)×124)]÷2=(125×124)÷2=15 500÷2=7 750