Question 181243
i=i
i^2=-1
i^3=-i
i^4=1
:
so any multiple of i^4=1
:
divide 19 by 4 =4 and 3 left over so 
:
{{{i^19=i^16*i^3}}} = 1(-i)=-i
:
{{{i^-19 =1/(i^19)=1/(-i)}}}multiply top and bottom by -i={{{-i/-1=i}}}
:
answer is i