Question

Soal tentang Barisan dan deret, tolong di jawab dengan benar beserta caranya ya​

Answer 1

Penjelasan dengan langkah-langkah:

1. barisan aritmatika

-1, 4, 9, 14, .......

a = -1

b = 4 - (-1)

b = 5

Un = a + (n - 1)b

U₁₅ = -1 + (15 - 1)5

U₁₅ = -1 + (14)5

U₁₅ = -1 + 70

U₁₅ = 69

2. barisan geometri

-5, 10, -20, 40, ...

a = -5

r = U₂/U₁ = 10/(-5)

r = -2

Un = arⁿ⁻¹

U₁₅ = -5(-2)¹⁵⁻¹

U₁₅ = -5(-2)¹⁴

U₁₅ = -5(2)¹⁴ ---berpangkat genap (-2) jadi positif

U₁₅ = -5(16.348)

U₁₅ = -81.920