concave downward,concaveconvex

concave downwardis also calledconcaveorconvex upwardconcave
求f concave upward 和 downward的范围
concave推出新配色足球鞋
y'' 0 (concave upward(=定义三中的convex):y=x^2 concave downward
求f concave upward 和 downward的范围