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va rog ajutati-ma

 

75+80+85+90+95+100....555

 

 



Răspuns :

Suma Gauss =a+b+c+..n=(n+a)*[(n-a):(b-a)+1]:2

75+80+85+90+95+100....555=(555+75)*[(555-75):5+1]:2=630*97:2=30555

5(15+16+17+...+111)

5* (15+111)*97/2

5* 126*97/2

5* 63*97= 30555