Question

Calculeaza prin metoda gauss 2+4+6+...+158=?

Answer 1

$\displaystyle 2+4+6+...+158=2(1+2+3+...+79)=2 \times \frac{79(79+1)}{2} = \\ \\ =2 \times \frac{79 \times 89}{2} =\not 2 \times \frac{6320}{\not2} =6320$