Jumlah deret geometri tak hingga √2 + 1 + 1/2√2 + 1/2 + ... adalah
Misal :
a = √2
r = U₂ ⇒ r = 1 ₓ √2 = 1 √2
U₁ √2 √2 2
S~ = a = √2 × 1 + 1/2√2
1 - r 1 - 1/2√2 1 + 1/2√2
= √2 + 1 = √2 + 1 = 2√2 + 2 = 2(√2 + 1)
1 - 1/2 1/2