Diketahui suku pertama (a) = 1 beda (b) = U₂-a = 3-1 = 2 --> b = 2 n = 99 Ditanya jumlah 99 suku pertama. Sn = (n/2)(a+Un) Sn = (n/2)(a+a+b(n-1)) Sn = (n/2)(2a+b(n-1)) S₉₉ = ⁹⁹/₂ (2(1)+2(99-1)) S₉₉ = ⁹⁹/₂ (2(1+99-1)) S₉₉ = ⁹⁹/₂ (2(99)) S₉₉ = 99² S₉₉ = 9801 Jumlah 99 suku pertama = 9801
Verified answer
Diketahui
suku pertama (a) = 1
beda (b) = U₂-a = 3-1 = 2
--> b = 2
n = 99
Ditanya jumlah 99 suku pertama.
Sn = (n/2)(a+Un)
Sn = (n/2)(a+a+b(n-1))
Sn = (n/2)(2a+b(n-1))
S₉₉ = ⁹⁹/₂ (2(1)+2(99-1))
S₉₉ = ⁹⁹/₂ (2(1+99-1))
S₉₉ = ⁹⁹/₂ (2(99))
S₉₉ = 99²
S₉₉ = 9801
Jumlah 99 suku pertama = 9801