Question

URGENT!
Efectuati:

2 supra n+1 plus 4 supra n+1 plus 6 supra n+1 plus .... plus 2n supra n+1 = ?

Answer 1

E=1/(n+1)(2+4+...+2n)=1/(n+1)·2(1+2+...+n)=1/(n+1)·2·n·(n+1)/2=n