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algebra intermediate
Problem
If is a real number and , what are the possible values for ? Use interval notation to express your answer.
Solution
Factoring the quadratic gives , which means that and must have opposite signs, since the product of two factors with the same sign is positive. Now, we split into four cases. If , then both factors are negative. If , both factors are positive. If or , one of the factors is zero. If , is negative and is positive, meaning the inequality is satisfied. So our only possible range is , giving interval notation of .
Final answer
(1,6)