a) Q reprezinta multimea numerelor rationale, adica fractiile si numerele naturale.
√9n+6= 3n+6 Oricare ar fi n numar natural, 3n+6=un numar natural sau rational --> 3n+6∈ Q
c) ma= (a+b) ÷ 2
ma=(17 -12√2 +17 +12√2) ÷ 2
ma= 34÷2=17
mg=√a·√b
mg=√(17 -12√2) (17 +12√2)
mg=√289+204√2-204√2-288
mg=√1=1