Other Derivative Rules 1. For what values of x does the graph of f (x) = x - 2 cos x have a horizontal tangent on the interval [0, 2x]. 2. Determine for which intervals the function f (x) = xex has a positive rate of change. MCV 4U0 Name: Date: 3. Determine the equation of the tangent defined by y = e* + sin x at (0, 1). 4. Determine the equation of the tangent to the curve defined by y = 2e3x that is parallel to the line -6x + y = 2