Answer:
= 4
Step-by-step explanation:
There is a common ratio r between consecutive terms , that is
r = - 20 ÷ 4 = 100 ÷ - 20 = - 5
This indicates the sequence is geometric with nth term ( explicit formula )
= a₁
where a₁ is the first term and r the common ratio
Here a₁ = 4 and r = - 5 , then
= 4
