Total Increment

the increment produced in a function of several variables by (in general nonzero) increments ∆x₁, Δx₂, ….,∆x_n produced in these variables. Under certain conditions (for example, if all the partial derivatives are continuous), the total increment may be expressed as the sum of the total differential—a linear function of the increments ∆x₁∆x₂,….∆X_n — and a term that is infinitestimal in comoarison with