Răspuns :
[tex]A = \left\{x\:\in\:\mathbb{{N}^{*}} \: | \: 2x + 3 < 9 \right\}[/tex]
[tex]2x + 3 < 9[/tex]
[tex]2x < 9 - 3[/tex]
[tex]2x < 6 \: | \div 2[/tex]
[tex]x < 3 = ( - \infty ,3)[/tex]
[tex]x \: \in \: \mathbb{{N}}^{*} = > x \: \in \: \left\{1,2\right\}[/tex]
[tex] = > A=\left\{1,2\right\}[/tex]
[tex]2x + 3 < 9[/tex]
[tex]2x < 9 - 3[/tex]
[tex]2x < 6 \: | \div 2[/tex]
[tex]x < 3 = ( - \infty ,3)[/tex]
[tex]x \: \in \: \mathbb{{N}}^{*} = > x \: \in \: \left\{1,2\right\}[/tex]
[tex] = > A=\left\{1,2\right\}[/tex]