Answer:
= 2
Step-by-step explanation:
The n th term of a geometric sequence is
= a
where a is the first term and r the common ratio
Given
= - 8, then ar = - 8 → (1)
Given
= 512, then a
= 512 → (2)
Divide (2) by (1)
=
, thus
r³ =- 64 ( take the cube root of both sides )
r = = - 4
Substitute r = - 4 into (1)
a(- 4) = - 8
- 4a = - 8 ( divide both sides by - 4 )
a = 2
Thus
= 2