Question

Write a RECURSIVE and EXPLICIT model for the following geometric sequence. 3, 15, 75, 375, 1875, ...

Answer 1

Explanation:

Common ratio (r) = 2nd term / 1st term = 15/3 = 5

Recursive formula:

`a_(n)=a_(n-1)*r \\\\a_(n)=a_(n-1)*5\\=5a_(n-1)`

Explicit formula:

a = first term = 3

`a_(n)=ar^(n-1)\\\\a_(n)=3*(5)^(n-1)\\`