Spot the value that is NOT purely imaginary

Exercise and reference answers

Questions

1. Items

   1. i⁴
   2. 3i
   3. −5i
   4. 2i

   Reason

   i⁴ = 1, which is real, not imaginary.

   Odd item

   i⁴

2. Items

   1. i²
   2. i
   3. −1
   4. i⁶

   Reason

   i is imaginary; the others all equal −1 (real).

   Odd item

   i