Question

Даю 100 баллов срочно!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

Answer 1

$z_{n} = \frac{n + 4}{2}$

а)

$z_{1} = \frac{1 + 4}{2} = \frac{5}{2} = 2.5 \\ z_{2} = \frac{2 + 4}{2} = \frac{6}{2} = 3 \\ z_{3} = \frac{3 + 4}{2} = \frac{7}{2} = 3.5 \\ z_{4} = \frac{4 + 4}{2} = \frac{8}{2} = 4 \\ z_{5} = \frac{5 + 4}{2} = \frac{9}{2} = 4.5$

b)

$S_{n} = \frac{z_{1} + z_{n}}{2} \times n \\ S_{10} = \frac{z_{1} + z_{10}}{2} \times 10 = 5(z_{1} + z_{10})\\ z_{10} = \frac{10 + 4}{2} = \frac{14}{2} = 7 \\ S_{10} = 5(2.5 + 7) = 5 \times 9.5 = 47.5$