First off, if z = x + yi with x,y e R

then, (z) = x - yi with x,y e R (It's the complex conjugate)

Now, let w = [(z)z]^(-1)[(z)]

Use the above formula for w to find the multiplicative inverse of z = 2 + i. Answers to be in the form a + bi with a,b e R.

Any advice is greatly appreciated. Thanks in advance.