Question

Hitunglah deret bil berikut.
A. 1+3+5+7+........+71.
B. 50+45+40+.......+15​

Tolong jawab besok dikumpul

Answer 1

DERET ARITMATIKA

Jawab:

A) 1 + 3 + 5 + 7 + ... + 71

a = 1

b = 2

Un = 71

Un = a + (n - 1) b

71 = 1 + (n - 1) 2

70 = 2n - 2

2n = 72

n = 36

S36 = ..?

Sn = (n/2) (2a + (n - 1) b

S36 = (36/2) (2 (1) + (36 - 1) 2)

S36 = 18 (72) = 1296

B) 50 + 45 + 40 + ... + 15

a = 50

b = -5

Un = 15

Un = a + (n - 1) b

15 = 50 + (n - 1) (-5)

-35 = 5 - 5n

-5n = -40

n = 8

S8 = ...?

Sn = (n/2) (2a + (n - 1) b)

S8 = (8/2) (2 (50) + (8 - 1) (-5))

S8 = 4 (100 + (-35)

S8 = 4 (65) = 260

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Detil Jawaban

• Mapel : Matematika
• Kelas : 11
• Materi : Bab 7 - Barisan dan Deret
• Kata kunci : Deret aritmatika
• Kode soal : 2
• Kode kategorisasi : 11.2.7