What is the common ratio of the geometric sequence: 128, -16, 2, -1/4, …?
Explanation also solves the rest of the sequence structure!
Let any term in this sequence be
Let a constant be k
let the ratio be r
Two points to note:
it is reducing so
The sequence alternates positive to negative so involves
Consider the alternating +ve and -ve
To find r ignore the
You are not asked to find the value of k.
But you could by
for a quick check I select