Question

determ.elem.multimiiA={x€N|63/2x+1€N}

Answer 1

A={x∈N|63/(2x+1)∈N}
63/(2x+1)∈N
divizorii lui 63  sunt 1,3,7,9,21,63
2x+1 = 1    x=0
2x+1 = 3    x=1
2x+1 = 7    x=3
2x+1 = 9    x=4
2x+1 = 21    x=10
2x+1 = 63    x=31

A={0,1,3,4,10,31}