Question

Hasil dari 2 + 2√2 + 4 + 4√2 +...+ 64

Answer 1

Rasio = r = 2√2/2 = √2
Un = ar^(n - 1)
64 = 2 . √2^(n - 1)
64/2 = (2^(1/2))^(n - 1)
32 = 2^((n-1)/2)
2^5 = 2^((n-1)/2)
5 = (n-1)/2
10 = n - 1
n = 11

S11 = a(r^11 - 1)/(r - 1) = 2(√2^11 - 1) /(√2 - 1)
= 2 (32√2 - 1) /(√2 - 1) dikali (√2 + 1)/(√2 + 1)
= 2 (64 + 32√2 - √2 - 1) / (2 - 1)
= 2(63 + 31√2)
= 126 + 62√2