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For f(x) = 2x4 - 4x2 + 3 find the following. (A) f'(x) (B) The slope of the graph of fat x = - 3 (C) The equation of the tangent line at x = - 3 (D) The value(s) of x where the tangent line is horizontal (A) f'(x) = (B) At x = - 3, the slope of the graph of f is (C) At x = - 3, the equation of the tangent line is y = (D) The tangent line is horizontal at x = (Use a comma to separate answers as needed.)