Question

ДАЮ 45 балов Срочна надо развязать до 17:00

Answer 1

Ответ:

Объяснение:

1.1) S = $\frac{2a1 + d(n-1)}{2}$ × n

a1 = 3, d= a2-a1 = 7-3=4, n = 15

S = $\frac{6 + 4(15-1)}{2}$ × 15 = 31 × 15 = 465

1.2) S = $\frac{b1}{1-q}$

b1 = 8, q = b2/b1 = 4/8 = 0.5

S = $\frac{8}{0.5}$ = 8×2 = 16

1.3) S = $\frac{b1(q^{n}- 1) }{q - 1}$

b1 = 32, q=3, n = 6$\frac{40 - 55}{2}$

S = $\frac{32 (3^{6} -1)}{3-1}$=  $\frac{32*728}{2}$ = 16*728 = 11648

2.1) S = $\frac{2a1 + d(n-1)}{2}$ × n

d = a3-a2 = 10-15 = -5, a1 = a2-d = 15+5 = 20, n=12

S = $\frac{40 - 55}{2}$ × 12 = -90

2.2) S = $\frac{b1(q^{n}- 1) }{q - 1}$

q²= b3/b1= 1/9, q=1/3, n=4

S = $\frac{81(1/81 - 1)}{1/3 - 1}$ = $\frac{-80}{-2/3}$ = 120

2.3) b1 = 5, b5 = 80

b5 = b1 * $q^{4}$

$q^{4}$= 80/5 = 16

q = 2

b2 = b1 * q = 5 * 2 = 10

b3 = b1 * $q^{2}$ = 5 * 4 = 20

b4 = b1 * $q^{3}$ = 5 * 8 = 40