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Ionutcatalin2006
a fost răspuns

Calculeaza sumele a) 2+4+6+...+2018
b) 5+10+15+...2020
c)35+38+41+...103

Răspuns :

GalaxyAngel
a) 2018-2+1=2017 (numere)
2017•(2017+1): 2=2017•2018: 2=2017•1009=1.035.153

b) 2020-5+1=2016 (numere)
2016•(2016+1): 2=1008•2017=2.033.136

c) 103-35+1=69 (numere)
69•(69+1): 2=69•70: 2=69•35=104

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