Answer to Question #60045 in Abstract Algebra for sajid

Question

Q. prove that
(i) H={a+ib ЄC, a2+b2=1} is a subgroup of C, Where C is complex number.
(ii) H be a set of real number a+b√2 where a,b ϵ Q. Show that H be a subgroup of non-zero real no. under *.