Algebra-1

Question Analysis
This question requires students to find the first term of a geometric sequence given two non-adjacent terms, the 5th and 7th terms.

Key Concept Explanation
The key concept here is using the explicit formula for geometric sequences, (), and setting up equations to solve for and .

Step-by-step Solution
1. Use the explicit formula for the 5th term:
2. Use the explicit formula for the 7th term:
3. Divide the second equation by the first:
4. Solve for

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