Demonstrati numerele intregi n pentru pare au loc inegalitatile:

a)
[tex] \frac{1}{5} < \frac{1}{n } < \frac{1}{2} [/tex]

b)
[tex] \frac{7}{2 } < \frac{n}{2} < \frac{22}{4} [/tex]

c)
[tex] - \frac{1}{3 } < \frac{n + 2}{6} < \frac{3}{2} [/tex]

d)
[tex] - \frac{8}{9 } < \frac{2 \times - 1}{18} < - 1.(6)[/tex]
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