Question

8. Given a geometric sequence, find az ifa1 = 729 and a2 = – 243.

Answer 1

Given a1=729 , a2= -243

Common ratio r= a2/a1= -243/729

r= -1/3

`\begin{gathered} \text{For a geometric sequence, } \\ a_n=a_1r^(n-1) \\ a_7=\text{ 729(}(-1)/(3))^(7-1) \\ =729((-1)/(3))^6 \\ 729\text{ (}(1)/(729)) \\ =1 \end{gathered}`