Question

se da multimea A ={x apartine N/5x-1>sau egal 34 si 7x+1 <92}.Determinati multimile B={x apartineA/x e patrat perfect} ; C={x apartine A /2x e patrat perfect sau 2x +1 e patrat perfect }

Answer 1

A ={x apartine N/5x-1≥ 34 si 7x+1 <92}
 5x-1≥34    5x≥35   x≥7
7x+1<92    7x<91  x<13
A={7,8,9,10,11,12}

B={x apartineA/x e patrat perfect}  ⇒ B={9}


C={x apartine A /2x e patrat perfect sau 2x +1 e patrat perfect
C={8,12}
pentru ca  :
2*8=16  patrat perfect
2*12+1=25 patrat perfect