Isi suku ke n dari 2,9,16,23

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2, 9, 16, 23, …

a = 2
b = 7

suku ke n

Uₙ = bn + (a – b)
Uₙ = 7n + (2 – 7)
Uₙ = 7n – 5 ✔️

atau

Uₙ = a + (n – 1) b
Uₙ = 2 + (n – 1) 7
Uₙ = 2 + 7n – 7
Uₙ = 7n – 5 ✔️