If {{MATH_120}} has a local extremum at {{MATH_121}} and {{MATH_122}} is differentiable at {{MATH_123}}, then {{MATH_124}}. {{CMD_125}} {{CMD_126}} Does Fermat's Theorem say that if {{MATH_127}}, then {{MATH_128}} has a local extrema at {{MATH_129}}? {{CMD_130}} {{CMD_131}}yes{{CMD_132}} {{CMD_133}}no{{CMD_134}} {{CMD_135}} {{CMD_136}} Consider {{MATH_137}}, {{MATH_138}}, but {{MATH_139}} does not have a local maximum or minimum at {{MATH_140}}. {{CMD_141}} {{CMD_142}}