Question

Calculaţi: a) 1+ 2+ 3+ +85 = b) 1+ 2+ 3+ + 348 = ) (1+2+3+ *** *** +17) + (1+2+3++200)
va rog rezolvarea!
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Answer 1

a) 1+2+3+...+85=85×(85+1)=

85×86=7.310

b)1+2+3+...+348=348×(348+1)=

348×349=121.452

c) (1+2+3+...+17)+(1+2+3+...+200)=

17×(17+1)+200×(200+1)

17×18+200×201=306+40.200=

40.506