Question

5 si 6 VA roggg!!!!! OFER coroana!!!!

Answer 1

4.
$\frac{1}{19} + \frac{2}{19} + ... + \frac{38}{19} = \\ = \frac{1 + 2+... + 38 }{19} = \frac{ \frac{38 \times 39}{2} }{19} = \\ = \frac{19 \times 39}{19} = 39 \: e \: nr \: natural$
$4. \frac{1}{19} + \frac{2}{19} + ... + \frac{38}{19} = \\ = \frac{1 + 2+... + 38 }{19} = \frac{ \frac{38 \times 39}{2} }{19} = \\ = \frac{19 \times 39}{19} = 39 \: e \: nr \: natural \\ 5. \\ \frac{4}{3} < \frac{ {n}^{2} }{9} < \frac{11}{6} \\ \frac{4}{3} < \frac{ {n}^{2} }{9} = > \frac{12}{9} < \frac{ {n}^{2} }{9} \\ deci \: n \geqslant 4 \\ \frac{ {n}^{2} }{9} < \frac{11}{6} = > \frac{ {n}^{2} \times 2}{18} < \frac{33}{18} \\ = > {n}^{2} < \frac{33}{2} \\ = > {n }^{2} < 16.5 \\ deci \: 12 < {n}^{2} < 16.5 \\ = > n = 4$
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