Matematika Sekolah Menengah Pertama Soal nomor 10 bantu dong kakgak ngerti cara kerjanya nih​

willakeeblerulv – March 06, 2023

Soal nomor 10 bantu dong kak
gak ngerti cara kerjanya nih​

n = 15

U5 = 23

U10 = 33

beda ( b )

(33 - 23) / (10 - 5)

10 / 5

2

b = 2

Mencari suku pertama (a)

Un = a + ( n - 1 ) b

U5 = 23

23 = a + ( 5 - 1 ) 2

23 = a + 8

23 - 8 = a

a = 15

Banyak Kursi ( Sn )

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

S15 = 15/2 ( 2 ( 15) + (14) 2 )

S15 = 7,5 (30 + 28)

S15 = 7,5(58)

S15 = 435

Jawab = A

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