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Calculeaza suma: 35+38+41+...+104

Răspuns :

35+38+41+...+104 =

= 3×1 +32 + 3×2+32 + 3×3+32 +...+ 3×24+32 =

= 3×(1+2+3+...+24) + 32 + 32 +...+32 de 24 ori =

= 3 × 24 × 25 : 2 + 32 × 24 =

= 3 × 12 × 25 + 768 =

= 900 + 768 =

= 1 668