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calculati sumele a) 1+2+3+ ....+ 50

Răspuns :

1+2+3+4+5+6+7+8+9+10+11+12+13+14+15+16+17+18+19+20+21+22+23+24+25+26+27+28+29+30+31+32+33+34+35+36+37+38+39+40+41+42+43+44+45+46+47+48+49+50=1275



deci faci (50-1):1+1=50asta este nr de termeni si pentru a calcula suma trebuie sa faci (50+1)*50:2=51*25=1275