Question

Determinati multimea A={ x apartine Z, -5 supra 2x+3 apartine N}

Answer 1

2x+3| -5
x∈Z    ⇒ 2x+3 ∈{-1,1,-5,5}

2x+3=-1  2x=-4  x= -2∉N
2x+3=1   2x=-2  x=-1∉N
2x+3=-5  2x=-8  x=-4∉N
2x+3=5   2x=8   x=4∈N  ⇒A={4}

Answer 2

2x+3={-1;1;-5}
2x+3=-1=>x=-2
2x+3=-5=>x=-4
2x+3=1=>x=-1
A={-2;-4;-1}