Differentiation Definition
Differentiation is the rate of change of a function with respect to one of the variables. It is something like finding the slope of the tangent line of a function at a point. We can define differentiation of a function f(x) with respect to x as f’(x) = lim(h->0)[f(x+h) – f(x)]/h
Partial Differentiation
A function in two variables given by f(x,y) when differentiated by keeping one of the variables constant, like differentiating y with respect to x keeping y constant we get what is called Partial differentiation of the function, it is denoted as doe(f)/doe(x) or fx when it is with respect to x and when the function in two variables is differentiated with respect to y keeping x constant it is denoted as doe(f)/doe(y) or fy.
For instance, let us find the partial differentiation of the function, f(x,y) = 2x^2y+ 3x +y
Solution: Keeping y constant let us differentiate first with respect to x, we get
fx = doe(f)/doe(x) = doe/doe(x) [2x^2y+3x+y]
= doe/doe(x)[2x^2y] + doe/doe(x) [3x] + doe/doe(x) [y]
= 4xy +3 +0 = 4xy + 3
Now keeping x constant let us differentiate the function with respect to y, we get
fy = doe(f)/doe(y) = d/dy [2x^2y+3x+y]
= doe/doe(y)[2x^2y] = d/dy[3x] + d/dy [y]
= 2x^2 + 0 + 1 = 2x^2 + 1
So, the partial differentiation of the funcntion f(x,y) = 2x^2y+3x + y is fx= 4xy =3 and fy =2x^2+1
Implicit Differentiation Solver
In Implicit Differentiation the differentiation is done with respect to x when the given function involves two variables, x and y. But here we do not assume the variable y to be constant, y treated as it is. Usually x is assumed to be the independent variable and the variable y is assumed to be the function of x, the independent variable. For differentiation, chain rule is applied with respect to x followed by some algebraic solving steps to get dy/dx. The formula for Implicit Differentiation solver is, given a function F(x,y) equals zero, which defines a differential relationship of the two variables x and y, then,
dy/dx = - [doe(F)/doe(x)]/[doe(F)/doe(y)] here, doe(F)/doe(x) is the partial derivative of F with respect to x and doe(F)/doe(y) is the partial derivative of F with respect to y.
Let us solve the Implicit differentiation of the function, x^3y^2- xy = 5
Solution: Implicit differentiation, dy/dx [x^3y^2 – xy] = dy/dx [5]
Applying chain rule, we get
dy/dx [x^3y^2] – dy/dx [xy] =0
3x^2y^2 + x^3. 2y. dy/dx – 1.y – x. 1. dy/dx = 0
(2x^3y- x) dy/dx = y – 3x^2y^2
dy/dx = [y-3x^2y^2]/[2x^3y – x]
Know more information on Differentiation and Differential Equations.
