Let {{MATH_69}} be an open interval. {{CMD_70}} {{CMD_71}} If {{MATH_72}} for all {{MATH_73}} in {{MATH_74}}, then the graph of {{MATH_75}} is concave up on {{MATH_76}}. {{CMD_77}} If {{MATH_78}} for all {{MATH_79}} in {{MATH_80}}, then the graph of {{MATH_81}} is concave down on {{MATH_82}}. {{CMD_83}} {{CMD_84}}