dz = Fxdx+Fydy；
Given that x and y are functions of t, directly find dx = xtdt and dy = ytdt, and divide both sides of dz = fxdx+fydy by dt to get the total differential.
Equation. That is dz = (fxxt+fyyt) dt;
Simply substituting into the original formula is similar to finding the 1 meta function directly.
Order: z = f (x, y);
Then: δ z/δ x = δ f/δ x+(δ f/δ y) * (δ y/δ x)
Replace the sign of the derivative with δ, δ f/δ x This is the derivative of x that can be seen in the expression! Δ z/Δ x is the relationship between the rate of change of z caused by the change of x.
Extended data
The definition of partial derivative is as follows:
The essence of derivative and partial derivative is the same, which is the limit of the ratio of function value change to independent variable change when the independent variable changes to zero.
The partial derivative is the rate of change of a function at a certain point along the positive direction of the coordinate axis.
The difference is:
Derivative refers to the rate of change of the function y = f (x) at a certain point in the unary function along the positive direction of the X axis; Partial derivative refers to the rate of change of the function y = f (x 1, x2, …, xn) at a certain point along a certain coordinate axis (x 1, x2, …, xn).