Given the graph of the function f below, determine all intervals where f (x) is concave down on the open interval (-9, 9). Drag the yellow point to see the slopes of the tangent lines. f'(-8.9) = -1.00124 Graph of f 15 10 -10 -8 -6 -4 -2 2 -5 -10 -15 Answer: Submit Answer OF S ( ) All Real Numbers DELL