If {{MATH_91}} and {{MATH_92}} are differentiable and {{MATH_93}} is a constant, then {{CMD_94}} {{CMD_95}}{{CMD_96}} {{MATH_97}}, {{CMD_98}} {{MATH_99}}, {{CMD_100}} {{MATH_101}}. {{CMD_102}} {{CMD_103}} We will only prove part~{{CMD_104}} above; the rest are similar. Write with me {{CMD_105}} {{ENV_106}} {{CMD_107}} {{CMD_108}} {{CMD_109}}