Math2.org Math Tables: Complexity

Rationalle that 1/i = -i

We know that by definition
  i = ( -1 )
Similarly,
  i*i = ( -1 ) * ( -1 ) = ( -1 )² = -1
by some algebra we get
  i*i = -1
  -i*i = 1     (multiply both sides by -1)
  -i = 1/i     (divide both sides by i)