The question is an illustration of geometric progression.
From the question, we have:
[tex]T_1= 1[/tex] ---- the first week
[tex]r = 2[/tex] ---- The rate at which the distance increases each week.
When a sequence has a common ratio, the sequence is said to be a geometric sequence.
The Recursive function.
We have given that
[tex]T_1= 1[/tex] ---- the distance in the first week
The second week would be:
[tex]T_2 = r \times T_1[/tex]
For the third week, the distance would be:
[tex]T_3 = r \times T_2[/tex]
Express 2 as 3 - 1
[tex]T_3 = r \times T_{3-1}[/tex]
Replace 3 with n, to get the distance for the nth week
[tex]T_n = r \times T_{n-1}[/tex]
Substitute 2 for r
[tex]T_n = 2 \times T_{n-1}[/tex]
[tex]T_n = 2T_{n-1}[/tex]
Hence, the recursive function is: [tex]T_n = 2T_{n-1}[/tex]
Explicit function
The nth term of a geometric sequence is:
[tex]T_n = T_1 \times r^{n-1}[/tex]
Substitute values for [tex]T_1\\[/tex] and r.
[tex]T_n = 1 \times 2^{n-1}[/tex]
[tex]T_n = 2^{n-1}[/tex]
Hence, the explicit function is: [tex]T_n = 2^{n-1}[/tex]
Read more about geometric sequence at:
https://brainly.com/question/18109692