Question

Evaluate sigma(n=1 to 13) (i^n+i^(n+1))

Answer 1

For each value of n, we get a series.....

=i+2(i^2)+2(i^3)+2(i^4)+.........+(i^14).

=i+2[(i^2)+(i^3)+(i^4)+.......+(i^13)]+i^14.