Question

The first two terms of a geometric sequence are a1 = 1/3 and a2 = 1/6. What is a8, the eighth term?

Answer 1

Answer:

B

Step-by-step explanation:

Given the sequence is geometric then the common ratio r is

r = $\frac{a_{2} }{a_{1} }$ = $\frac{\frac{1}{6} }{\frac{1}{3} }$ = $\frac{1}{2}$

The n th term of a geometric sequence is

$a_{n}$ = $a_{1}$ $(r)^{n-1}$

                       = $\frac{1}{3}$ × $(\frac{1}{2}) ^{7}$

                      = $\frac{1}{3}$ × $\frac{1}{128}$ = $\frac{1}{384}$

Answer 2

Answer:

B. 1/384

Step-by-step explanation:

a1=1/3

a2 = 1/6

The constant factor is 1/2

a1=2/3*1/2

a2=2/3*1/2^2

a8=2/3*(1/2)^8

2/3*1/256