Answer:
a₂₀ = 77
Step-by-step explanation:
There is a common difference between consecutive terms , that is
5 - 1 = 9 - 5 = 13 - 9 = 4
This indicates the sequence is arithmetic with nth term
[tex]a_{n}[/tex] = a₁ + (n - 1)d
where a₁ is the first term and d the common difference
Here a₁ = 1 and d = 4 , then
a₂₀ = 1 + (19 × 4) = 1 + 76 = 77
