Complex Numbers

Definition:   i = sqrt(-1)     so  i^3 =  i^2 x i  =  -1 x i =  -i

i⁴ⁿ⁺¹=i

i⁴ⁿ⁺²=-1

i⁴ⁿ⁺³=-i

i⁴ⁿ=1

3 is 4(0)+3

Therefore i³=-i