Answer:
a₁₂ = 20971520
Step-by-step explanation:
The nth term of a geometric sequence is
[tex]a_{n}[/tex] = a₁[tex](r)^{n-1}[/tex]
where a₁ is the first term and r the common ratio
Here a₁ = 5 and r = a₂ ÷ a₁ = 20 ÷ 5 = 4 , then
a₁₂ = 5 × [tex]4^{11}[/tex] = 5 × 4194304 = 20971520
