Răspuns :

Denisaglodianuid

Răspuns:

6+9+12+...+39

nr termeni (39-6):3+1=33:3+1=11+1=12

(6+39)*12:2=45*12:2=45*6=270

Explicație pas cu pas:

suma Gauss

Kawaiimathid

6+9+12...+39=3(2+3+4+...+13)=3(1+2+3+...+13) -1=3*[(13*14)/2-1] =3*(182/2-1) =3*(91-1) =3*90=270

Kawaiimath

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