Dik = U1 = 3000 B = 500 Sn = 630.000 Dit = n ? Tolong bantu jawab buat bsk, jgan lupa pke caranya

Mapel : Matematika
Bab: Barisan/Deret

U1 = a = 3.000
b = 500
Sn = 630.000

Sn = n/2(2a + (n-1)b)
630.000 = n/2(2(3.000) + (n -1)500)
630.000 = n/2(6.000 + 500n - 500)
630.000= n/2(5.500 + 500n)
630.000 = 5.500n/2 + 500n^2/2
630.000 = 2.750n + 250n^2
0 = 250n^2 + 2.750 - 630.000
0 = 250(n - 45)(n + 56)

n - 45 = 0
n = 45 (memenuhi)

n +56 = 0
n = -56 (tidak memenuhi)

n = 45