Question

Cum se rezolva acesta operatie 4+8+12+.....+1996

Answer 1

4+8+12+-----+1996=4(1+2+3+-----499)=4*124750=499000
1+2+3+----+499=499(499+1)/2=499*500/2=499*250=124750

Answer 2

$\displaystyle 4+8+12+...+1996=4(1+2+3+...+499)=4 \times \frac{499(499+1)}{2} = \\ \\ =4 \times \frac{499 \times 500}{2} =4 \times \frac{249500}{2} =4 \times 124750=499000$