Question

precizati cardinalul multimii A={ x| x∈N,36<x<120 si(72,x)=12}
cate elemente are?

Answer 1

daca (72;x)=12 ⇒ 12 | 72 si 12 | x inseamna ca x = M₁₂

=> card A = card {36<M₁₂<120} = card{4*12; 5*12; 6*12; 7*12; 9*12} = 5 ***