Question

5/4026+10/4026+...+10065/4026

Answer 1

Observam ca fractiile au acelasi numitor, astfel ca vom afla suma numaratorilor.

S = ( 5 + 10 + 15 + ........+ 10 065 ) / 4 026

S = 5 x ( 1 + 2 + 3 + .......+ 2 013 ) / 4026

S = 5 x 2 013 x ( 1 +  2 013 ) / 2 x 4 026

S = 5 x  2013 / 4 026  x  2014 / 2

S = 5 x 1 / 2 x 1 007

S = 5 035 / 2

S = 2 517,5