Algebra-1

Question Analysis
This question requires students to find the first term 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 first term and common ratio can be found by setting up and solving a system of equations.

Step-by-step Solution
1. Identify the given terms: and .
2. Use the explicit formula for the 3rd term: .
3. Use the explicit formula for the 5th term: .
4. Divide the equation for the 5th term by the equation for the 3rd term: .
5. Simplify the equation:

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