let p and q be complex numbers with |a|=|b|=|c|. (A) prove that if a root of the eqauation azsqaur+bz+c=0 has modulas equal to 1,then bsquar=ac

Since the modulus of one of the root is 1,it satisfies the condition for reality i.e. b^2 - 4ac > 0..which gives ur answer,,

We will repeatedly invoke the result that if |z| =1 then 

We have here three complex numbers with modulus 1,  where  is the root of the equation.

So, we have  ........................1 which can be written as 

Taking conjugates on both sides and using the result mentioned above, we have 

 which translates to ........................2

Multiplying 1 by b, we get .....................3

Subtracting 2 and 3, we get