What is the value of f(x) when f(x) = c, where c is any constant? How does the graph of f(x) look like?
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What is the derivative of f(x) = 3x^4 + 2x^2 - 5x + 7 with respect to x?
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What is the period of the cosine function f(x) = cos x? Does the graph of f(x) intersect the x-axis at any point other than the maximum and minimum points? Justify your answer.