Hitung U11 dan S11 dari barisan 256, 128, 64​

Barisan

a = 256

r = 128/256 =  1/2

un = a . rⁿ⁻¹

u11 = 256. 1/2 ¹¹⁻¹ = 2⁸. (2⁻¹)¹⁰

U11 =  2⁸. 2⁻¹⁰ = 2⁻² = 1/4

s11 =   a ( 1 – rⁿ)/ ( 1 – r)

s11 =  256 ( 1 – 1/2¹¹) / (1 – 1/2)

s11 =  256 (1 – 2⁻¹¹)  / (1/2)

s11 = 2 (256) (1 – 2⁻¹¹)

s11 = 2⁹ – 2⁻²

s11 = 2⁹ – 1/4