In a geometric sequence, the 5th term is 160 and the 7th term is 640. Find the common ratio r. The common ratio r is _______.
Answer & Analysis
Analysis
Question Analysis
This question requires students to find the common ratio of a geometric sequence given two non-adjacent terms. It tests their ability to set up and solve equations using the explicit formula for geometric sequences.
Key Concept Explanation
The key concept here is the relationship between terms in a geometric sequence, specifically how the common ratio can be found by dividing one term by another.
Step-by-step Solution
1. Identify the given terms: and .
2. Use the explicit formula for the 5th term: .
3. Use the explicit formula for the 7th term:
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