Final answer:
To find the common ratio in a geometric sequence without knowing the first term, divide each term by its previous term.
Step-by-step explanation:
In a geometric sequence, the common ratio is the ratio between any term and the previous term. To find the common ratio without knowing the first term, you can divide any term by its previous term.
For example, if the terms of a geometric sequence are 2, 4, 8, 16, the common ratio is found by dividing each term by its previous term: 4/2 = 2, 8/4 = 2, 16/8 = 2. Therefore, the common ratio is 2.