concave upward,concaveupward

f''(x) > 0 for all x in i, then the graph of f is concave upward
求f concave upward 和 downward的范围
f"(x) > 0 for all x in i, then the graph of f is concave upward
concave推出新配色足球鞋
concave 推出新配色 halo 足球鞋