Question

POTRZEBUJE NA JAK NAJSZYBCIEJ! DAJE NAJ!

Answer 1

Odpowiedź:

[tex]a_1 = - 4 \\r = 3[/tex]

więc

[tex]a_n = a_1 + (n - 1)*r = - 4 + ( n - 1)*3 = 3 n - 7\\oraz\\a_{n+1} = 3 n - 7 + r = 3 n - 7 + 3 = 3 n - 4\\a_{n+2} = 3 n - 4 + r = 3 n - 4 + 3 = 3 n - 1\\a_{n+3} = 3 n - 1 + r = 3 n - 1 + 2 = 3 n + 2[/tex]

zatem

[tex]\frac{a_n + a_{n+1} + a_{n+2} + a_{n + 3}}{4} + \frac{(3n -7) + (3 n - 4) + ( 3n - 1) + (3 n +2}{4} = 24,5/ * 4[/tex]

12 n - 10 = 98

12 n = 108 / : 12

n = 9

Odp.  Te wyrazy, to: [tex]a_9, a_{10} , a_{11}, a_{12}[/tex]

===============================

[tex]a_9 = 20, a_{10} = 23, a_{11} = 26, a_{12} = 29[/tex]

Szczegółowe wyjaśnienie: