Question

DOAR A SI D OFER 30 DE PUNCTE PLUS COROANA ,REPEDE​

Answer 1

Explicație pas cu pas:

N={1,2,3,4...+∞}

x=1 => 21:[(2•1)+1]=21:3= 7 ∈ N

x=2 => 21:[(2•2)+1]=21:5= 4,2∉N

x=3 => 21:[(2•3)+1]=21:7=3∈ N

x=4 => 21:[(2•4+1)]=21:9=2,(3)∉N

x=5 => 21:[(2•5+1)]=21:11=1,(90)∉N

x=6 => 21:[(2•6+1)]=21:13=1,615∉N

x=7 => 21:[(2•7+1)]=21:15=1,4∉N

x=8 => 21:[(2•8+1)]=21:17=1,235∉N

x=9 => 21:[(2•9+1)]=21:19=1,105∉N

x=10 => 21:[(2•10+1)]=21: 21=1∈N

A= {1, 3, 10}