Question

Barisan -12, -11½, -11, -10½ ....
Cari beda barisan?
Jika Un = 0, carilah nilai n?
Jika Sn = 0, carilah nilai n?

Answer 1

b = -11 1/2 - ( -12)
b = -11 1/2 + 12
b = 1/2


0 = -12 + (n - 1) 1/2
12 = (n-1)1/2
24 = n - 1
n = 25


0 = n/2 ( 2. -12 + (n - 1)1/2)
0 = n/2 ( -24 + n/2 - 1/2)
0 = n/2 ( -49/2 + n/2 )
0 = n ( -49 + n )
0 = -49n + n²
n² = 49n
n = 49