Question

Tolong bantu nomer 6 :)

Answer 1

Verified answer

U1 = 84
u2 = 80,5
un = n

maka beda barisan tersebut = u2-u1 = 80,5 - 84 = -3,5
un = a + (n-1)b = 0
84 + (n-1)(-3,5) = 0
84 - 3,5n + 3,5 = 0
87,5 = 3,5n
n = 87,5/3,5 = 25

Answer 2

Bab Barisan dan Deret
Matematika SMP Kelas VIII

b = U2 - U1
b = 80 1/2 - 84
b = - 3 1/2

Un = 0
a + (n - 1) b = 0
84 + (n - 1) . -3 1/2 = 0
(n - 1) . -7/2 = -84
n - 1 = -84 . (-2/7)
n = 24 + 1
n = 25