Jika sn=2n²(n-1),maka u5=...…..

Bab Barisan dan Deret
Matematika SMP Kelas IX

Sn = 2n² (n - 1)
Sn = 2n^3 - 2n²

Un = Sn - S(n - 1)
U5 = S5 - S4
U5 = (2 . 5^3 - 2 . 5²) - (2 . 4^3 - 2 . 4²)
U5 = (250 - 50) - (128 - 32)
U5 = 200 - 96
U5 = 104

# terima kasih #

sn=2n²(n-1),
S1 = 0          maka U1 = 0

S2 = 2x2²(2-1) = 8 maka U1 + U2 = 8 maka U2 = 8

S3 = 2x3²(3-1) = 36,  U1 + U2 + U3 = 36, U3 = 24

S4 = 2x4²(4-1) = 96 , U4 = 96-36 = 60

S5 = 2x5²(5-1) = 200, U5 = 200 - 96 = 104

jadi  U5=104