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Airi46
a fost răspuns

1+2+3+.........37

11+12+........50

3+6+7+.......93

2+4+6+........90

Răspuns :

Albatran
1+2+...+37=37*38/2=37*19=703

11+12+...50= (1+2+...+50)-(1+2+...+10)=50*51/2-10*11/2-1275-55=1220


aici modificam
3+6+9+..+93 =3(1+2+...+31)=3*31*32/2=1488


2+4+6+...+90=2(1+2+..+45)=2*45*46/2 =45*46==2070


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