Предмет: Алгебра, автор: Agustea

Срочно!!! Помогите пожалуйста

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Ответы

Автор ответа: Evgenia4836

Ответ:

Объяснение:

1) Sn= 1040

(2a1+d(n-1))*n/2=1040

(-10+6n-6)*n= 2080

n>0 n - целое число

6n²-16n-2080=0

3n²-8n-1040=0

D= 64+12480= 12544

n= (8+112)/6= 20

2) b1*b2*b3= 27

b1+b2+b3= 26

b1*b1*q*b1*q²=27

b1+b1*q+b1*q²=26

b1³q³=27

b1*q= 3

b1= 3/q

3/q+3/q*q+3/q*q²=26

3/q+3+3q=26

3+3q+3q²=26q

3q²-23q+3=0

D= 539- 36= 493

q1= (23-√493)/6 - не корень, так как прогрессия не убывающая

q2= (23+√493)/6

b1= (23+√493)/2

b2= (511+23√493)/6

b3= (5773+260√493)/9

( второе задание дано с ошибкой, сумма там должна быть другим числом).

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