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Question
Let f(x) = x3 − 6x2 + 9𝑥 + 18, then f(x) is strictly decreasing in ______
Options
(−∞, 1)
(3, ∞)
(−∞, 1) ∪ (3, ∞)
(1, 3)
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Solution
(1, 3)
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