Question

1+5+9+13+.....+181 dati factor comun pls dau 50 de puncte​

Answer 1

Explicație pas cu pas:

suma are 46 termeni

$1+5+9+13+.....+181 = 1 + (1 + 4) + (1 + 8) + ... + (1 + 180) = \underbrace{1 + 1 + 1 + ... + 1}_{46} + (4 + 8 + ... + 180) = 46 + 4 \cdot (1 + 2 + ... + 45) = 46 + 4 \cdot \dfrac{45 \cdot 46}{2} = 46 + 2 \cdot 2070 = \bf 4186$