Find the number of complex numbers z, such that the sum of z and the reciprocal of its conjugate equals the absolute value of the complex number z.
This section requires Javascript.
You are seeing this because something didn't load right. We suggest you, (a) try
refreshing the page, (b) enabling javascript if it is disabled on your browser and,
finally, (c)
loading the
non-javascript version of this page
. We're sorry about the hassle.
We can rephrase the problem in numerical form to be:
z + z ∗ 1 = ∣ z ∣
By letting z = x + i y and using Pythagoras to evaluate the absolute value:
x + i y + x − i y 1 = x 2 + y 2
Removing the fractions and simplifying:
x 2 + y 2 + 1 = x 2 + y 2
Let: a = x 2 and b = y 2 ,
( a + b + 1 ) 2 = a + b
a 2 + 2 a b + b 2 + 2 a + 2 b + 1 = a + b
a 2 + 2 a b + b 2 = − a − b − 1
( a + b ) 2 = − a − b − 1
As we have defined z = x + i y , x and y are real numbers and since a and b are the squares of real numbers, a and b are positive real numbers. Therefore, on this last line, the left hand side must be positive and the right hand side must be negative. Hence, there are 0 values for z .