you are interested in finding .
Think about what you would do if it were a rational number, but be more sophisticated.
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.