Students frequently confuse the differential {{MATH_288}} with the derivative {{MATH_289}}. Remember that the derivative tells us the {{CMD_290}}rate{{CMD_291}} of change at the point, while the differential {{MATH_292}} is an {{CMD_293}}estimated amount{{CMD_294}} of change. We will do that in our next definition. {{CMD_295}} Let {{MATH_296}} be a differentiable function, let {{MATH_297}} be a point in the domain of {{MATH_298}}, and let {{MATH_299}} be some quantity, called a {{CMD_300}}differential of {{MATH_301}}{{CMD_302}}. We define {{MATH_303}}, a differential of {{MATH_304}}, at a point {{MATH_305}} by {{MATH_306}}