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a fost răspuns

Calculati:
2*3+2*3^2+...+2*3^20
Calculati:
a) 2+2^2+2^3+2^4+...+2^20=?
2+2^2+2^3+2^4+...+2^200=?
Va rog ajutatima dau coronita !!!

Răspuns :

MissD
2*3=6=> 6 (1+2+..........+20)=6*20*21/2=6*21*10=126*10=1260
a) 2 (1+2+3+.........+20)=2*30*21/2=30*21=630
2(1+2+3+.......+200)=2*200*201/2=2*100*21=42*100=4300

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