Verified answer

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Verified answer

1) a₁ = 22      d = - 2

a₂₂ = a₁ + 21d = 22 + 21 * (- 2) = 22 - 42 = - 20

2) a₁ = - 126       a₂ = - 123

a₂ = a₁ + d

d = a₂ - a₁ = - 123 - (- 126) = - 123 + 126 = 3

a₁₅ = a₁ + 14d = - 126 + 14 * 3 = - 126 + 42 = - 84

3) a₁ = 16     d = - 3     aₙ = - 26

aₙ = a₁ + d(n - 1)

- 26 = 16 - 3(n - 1)

- 26 = 16 - 3n + 3

- 26 = 19 - 3n

3n = 19 + 26

3n = 45

n = 15

Число - 26 является членом этой прогрессии, это a₁₅ = - 26

4) a₅ = 5       a₉ = 13