Question

Tolong jawab beserta caranya

Answer 1

B = 3
U9 : U7 = 5 : 4
Un = 63 kursi
Sn = ?

U9 : U7 = 5 : 4
[a + (9 - 1)b]/[a + (6 - 1)b] = 5/4
(a + 8(3))/(a + 5(3)) = 5/4
(a + 24)/(a + 15) = 5/4 (kali silang)
4(a + 24) = 5(a + 15)
4a + 96 = 5a + 75
4a - 5a = 75 - 96
-a = -21
a = -21/-1 = 21 kursi

Un = 63
a + (n - 1)b = 63
21 + (n - 1)3 = 63
3(n - 1) = 63 - 21
3(n - 1) = 42
n - 1 = 42/3
n - 1 = 14
n = 14 + 1 = 15 baris kursi

Sn = n/2 (a + Un)
= 15/2 (21 + 63)
= 15/2 × 84
= 15 × 84/2
= 15 × 42 = 630 kursi (tidak ada jawaban)

maaf kalau salah
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