[tex]a)9 - 2x = - 21 - 7x[/tex]
[tex] - 2x + 7x = - 21 - 9[/tex]
[tex]5x = - 30[/tex]
[tex]x = - \frac{30}{5} [/tex]
[tex]x = - 6 \: \in \: \mathbb{Z}[/tex]
[tex]b)3(x + 1) = 11 - x[/tex]
[tex]3x + 3 = 11 - x[/tex]
[tex]3x + x = 11 - 3[/tex]
[tex]4x = 8[/tex]
[tex]x = \frac{8}{4} [/tex]
[tex]x = 2 \: \in \: \mathbb{Z}[/tex]
[tex]c)3x + 2 = 3(x + 1)[/tex]
[tex]3x + 2 = 3x + 3[/tex]
[tex]3x - 3x = 3 - 2[/tex]
[tex]0 = 1 = > ecuatia \: nu \: are \: sens[/tex]
[tex]d)5 + x - 2 = - x + 3[/tex]
[tex]x + x = 3 - 5 + 2[/tex]
[tex]2x = - 2 + 2[/tex]
[tex]2x = 0[/tex]
[tex]x = \frac{0}{2} [/tex]
[tex]x = 0 \: \in \: \mathbb{Z}[/tex]
[tex]e)2(x + 1) = 10 - x[/tex]
[tex]2x + 2 = 10 - x[/tex]
[tex]2x + x = 10 - 2[/tex]
[tex]3x = 8[/tex]
[tex]x = \frac{8}{3} \: \notin \: \mathbb{Z}[/tex]
