G ≠0,a,b,c,d∈R C H ≠0,a,b,c2d∈} c d)c a 2a√2b a,b,c,d∈Q 01 √20 a a,b,c,d∈Q 01{ | 0,a,b,c,d R} c d a b c d a b G           = { | 0,a,b,c,d Q} c d a b c d a b H           = | a,b, c,d Q} c d 2a 2b H { 0 1 2 0          =         | a,b, c,d Q} 2c d 2a b { 0 1 2 0 H          =        