Dik= barisan 1, 3, 9, 27 tentukan rumus suku ke-n U1 U2 U3 U4

Materi: Sequence and Series

1, 3, 9, 27 merupakan barisan geometri dgn
a = 1, r = 3/1 = 3.
Un = ar^(n-1) = 1(3)^(n-1)
= 1/3 × 3^n <<<<

Bab Barisan dan Deret
Matematika SMP Kelas IX

geometri
1, 3, 9, 27
r = 3 / 1 = 3

1] Un = a x rⁿ⁻¹
Un = 1 x 3ⁿ⁻¹
Un = 3ⁿ⁻¹

2] U1 = a = 3¹⁻¹ = 3⁰ = 1

3] U2 = 3²⁻¹ = 3¹ = 3

4] U3 = 3³⁻¹ = 3² = 9

5] U4 = 3⁴⁻¹ = 3³ = 27