\(D=\left\{x\inℕ|\left(x-1\right)⋮4;0< x< 18\right\}\)
\(D=\left\{x\inℕ|\left(x-1\right)⋮4;0< x< 18\right\}\)
D={1;5;9;13;17}
=> D = { x \({\displaystyle \in }\) N* / x = 4k+1 ; k \({\displaystyle \in }\) N* ; 0 < k < 5 }
~HT~
chỗ trống là thuộc nha