Remember that the multiplictive inverse of number is what you mutliply that number by in order to have a product of 1.
Examples of multiplicitive inverses
 2 & ½ because 2 • ½ = 1
 4 & ¼ because 2 • ¼ = 1
The multiplicitive inverse of any complex number a + bi is 1/(a + bi) . However, since i is a radical and in the denominator of a fraction. The same rules apply : rationalize the denominator. To rationalize the denominator just multiply by the complex conjugate of the original complex number( which is now in the denominator). Remember that multiplying two complex conjugates produces a real product, hence a rationalized denominator!

Related Page:
 Complex and Imagainary Numbers
 imaginary numbers
 complex numbers