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PLLLZ HELP Write a recursive formula for finding the nth term of each geometric sequence.
5, 20, 80, ...

a1 = 20, an = 4an − 1

a1 = 80, an = 4an − 1

a1 = 5, an = 4an − 2

a1 = 5, an = 4an − 1

Respuesta :

Poltergeist

Answer:

[tex]a_1 = 5,\\a_n =4 a_{n-1}[/tex]

Step-by-step explanation:

The first term of the geometric sequence is

[tex]a_1 =5[/tex].

The common ratio between the consecutive terms is

[tex]\dfrac{20}{5} = 4,[/tex]

[tex]\dfrac{80}{20} = 4;[/tex]

therefore, we see that the nth term is found by

[tex]a_n =4 a_{n-1}[/tex]

Thus, the recursive formula for the geometric sequence is

[tex]a_1 = 5,\\a_n =4 a_{n-1}.[/tex]