a) A={x€N | 4/x €N};
x/4/x →x:4/x
→x×x/4
x×x/4→x²/4
b) B=x€N | 3/x-1 €Z};
3/x-1 →x:3/x¹
→x×x¹/3
x¹×x¹/3→x²/3
c) C={x€Z | 9/2x+1 €Z};
2/9/2x+1→x×(2x+1)/9→2×z+z/9
d) D={x€Z | 2x-3/x+1 €Z}.
2x-3/x+1→2/(x+1)×3
2/x⁴+x³
-----SPER CA TE-AM AJUTAT❤❤❤-----
-----COROANA? -----
