s=2+4+6+8.........+500

Răspuns :

s=2+4+6+...+500
s=2(1+2+3+...+250)
s=2 x (250x251)/2
s=250x251
s=62750
Succes!
S=2+4+6+8+...+500
S=2×(1+2+3+4+...+250)
S=2×(250×251:2)
S=2×(62750:2)
S=2×31375
S=62750