Question

Calculaţi suma 1 + 4 + 7 + 10 + 13 + ... + 28 + 31.​

Answer 1

$ratia(diferenta) \:dintre \: termni \: estede \: 3 \\ = > (31 - 1) \div 3 + 1 = 30 \div 3 + 1 = \\ 10 + 1 = \\ 11 \: termni \\ suma = \frac{(31 + 1) \times 11}{2} \\ = \frac{32 \times 11}{2} = \frac{352}{2} = \\ 176 \: (suma)$

Sper ca te-am ajutat! Bafta!