Find f'(X) and approximate (to four decimal places) the value(s) of x where the graph of f has a horizontal tangent line. f(x) = 0.05x* - 0.2x³ – 1.8x? + 2.7x + 4 %3D f'(x) = 0.20x - 0.6x² – 3.6x +...

Extracted text: Find f'(X) and approximate (to four decimal places) the value(s) of x where the graph of f has a horizontal tangent line. f(x) = 0.05x* - 0.2x³ – 1.8x? + 2.7x + 4 %3D f'(x) = 0.20x - 0.6x² – 3.6x + 2.7 The graph of f has a horizontal tangent line at x = (Round to four decimal places as needed. Use a comma to separate answers as needed.)