Let be nonzero real numbers. Suppose that for each , where . Compute the maximum possible number of integers such that .
Solution
Let the answer be . If , there would exist two consecutive positive terms which contradicts the assumption that . Thus, . If , then the s must alternate between positive and negative. WLOG, assume and for each . Then, we have and . Multiplying the first equation over all gives us , while multiplying the second equation over all gives us . Thus, we must have . is possible by the following construction: .
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