Răspunsuri

2014-10-21T21:20:15+03:00
10
S=1+2+3+..+30

Solutie= 30· 31 :2=

11+22+33+....+330
11(1+2+3+.......30)= 11·30 ·31 :2=

5+10+15+......+150
5(1+2+3+...+30)= 5·30 ·31 :2=
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