Sketch the graph of each function. List the coordinates of where extrema or points of inflection occur. State where the function is increasing or decreasing, as well as where it is concave up or concave down.
The Attempt at a Solution
Critical Points: (2,-16) and (-2,16)
f''(x)=6x=0 , which makes x = 0 which gives the inflection point (0,0)..
I got all three of those points on the graph. I don't understand the concave up or concave down part and where the function is increasing or decreasing.