hasil dari: 1+2+4+8...+256 adalah A. 2^8 -1 B. 2^8 C.2^9 D.2^9 -1

Un= a+(n-1) b b=2-1 = 1
256=1+(n-1)1
256=1+1n-1
256=1n
n=256 = 2^8

Bab Barisan dan Deret
Matematika SMP Kelas VIII

^ = pangkat

1 + 2 + 4 + 8 + ... + 256 = ?

r = U2/U1
r = 2/1
r = 2

Un = 256
a . r^(n - 1) = 2^8
1 . 2^(n - 1) = 2^8
n - 1 = 8
n = 8 + 1
n = 9

Sn = a . (r^n - 1)/(r - 1)

S9 = 1 . (2^9 - 1)/(2 - 1)
S9 = 2^9 - 1

✩✩ D ✩✩