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1+4+7+10+...+541=
Cum se face ?


Răspuns :

 \\ [tex]n=(541-1):3+1 \\ n=540:3+1 \\ n=181 \\ S=(541+1)* \frac{181}{2} \\ S=542* \frac{181}{2} \\ S= \frac{542*181}{2} \\ \\ S= \frac{98102}{2} \\ S=49051 [/tex]