Answer:
Number of units possible in S are 4.
Explanation:
Given <em>S</em> is a set of complex number of the form where <em>a</em> and <em>b</em> are integers.
is a unit if
exists such that
.
To find:
Number of units possible = ?
Solution:
Given that:
Taking modulus both sides:
Using the property that modulus of product of two complex numbers is equal to their individual modulus multiplied.
i.e.
So,
......... (1)
Let
Then modulus of z is
Given that a and b are <em>integers</em>, so the equation (1) can be true only when (Reciprocal of 1 is 1). Modulus can be equal only when one of the following is satisfied:
(a = 1, b = 0) , (a = -1, b = 0), (a = 0, b = 1) OR (a = 0, b = -1)
So, the possible complex numbers can be:
Hence, number of units possible in S are 4.