Question

2+4+6+...+2n nu este p.p.
2•(1+2+3+...+n)=
2•(1+n)•n:2=(31+n)•n
​

Answer 1

2 + 4 + 6 + .. + 2n =

= 2·(1 + 2 + .. + n)

= 2×n×(n + 1) : n

= n×(n + 1) produs de numere consecutive ≠ patrat perfect