[tex]M=\left \{ n\:\in\:\mathbb{N} \:|\:6\leq 2n+4<20\right \}[/tex]
[tex]6 \leq2n + 4 < 20 \: | - 4[/tex]
[tex]2 \leq2n < 16 \: | \div 2[/tex]
[tex]1 \leq n < 8 = [1,8)[/tex]
[tex]n \: \in \: \mathbb{N} = > n \: \in \: \left\{1,2,3,4,5,6,7\right\}[/tex]
[tex] = > M=\left\{1,2,3,4,5,6,7\right\}[/tex]
