Question

A={x apartine IN/a=3la puterea n,n apartine lui IN,n<3}

Answer 1

n e [N ; n<3 => n e {0,1,2}
x e { 3 la 0, 3 la 1, 3 la 2}
x poate fi { 1,3,9} ( x e [N )
=>A={1,3,9}