Partial derivative - Wikipedia
https://en.wikipedia.org/wiki/Partial_derivativeIn mathematics, a partial derivative of a function of several variables is its derivative with respect to one of those variables, with the others held constant (as opposed to the total derivative, in which all variables are allowed to vary). Partial derivatives are used in vector calculus and differential geometry. The partial derivative of a function with respect to the variable is variously denoted by
Calculus III - Partial Derivatives
tutorial.math.lamar.edu › PartialDerivativesMay 31, 2018 · Here are the formal definitions of the two partial derivatives we looked at above. f x(x,y) = lim h→0 f (x+h,y)−f (x,y) h f y(x,y) = lim h→0 f (x,y+h) −f (x,y) h f x ( x, y) = lim h → 0. . f ( x + h, y) − f ( x, y) h f y ( x, y) = lim h → 0. . f ( x, y + h) − f ( x, y) h.