PROJECTENGRAM

IMPLICIT DIFFERENTIATION

Implicit Differentiation

Tags: #◇Computer Science #◇CSMATH1 #◇Problem Solving


◇Overview

We say an equation determines yy as one or more implicit functions of xx when yy is not isolated on one side of the equation. For such implicit equations, we use a technique called implicit differentiation to solve for dydx\frac{dy}{dx} (or y′y'). This involves differentiating both sides of the equation with respect to xx and applying the chain rule whenever yy is differentiated.

◇Important Formulas

The Chain Rule in Implicit Differentiation

When differentiating a term involving yy with respect to xx, apply the chain rule:
ddx[f(y)]=f′(y)⋅dydx\frac{d}{dx}[f(y)] = f'(y) \cdot \frac{dy}{dx}

◇Worked Examples

General Procedure for Implicit Differentiation:

  1. Differentiate both sides of the equation with respect to xx.
  2. Collect all terms containing dydx\frac{dy}{dx} on one side of the equation.
  3. Factor out dydx\frac{dy}{dx} from these terms.
  4. Solve for dydx\frac{dy}{dx} by dividing both sides by the factored expression.

Note: You can check your results by comparing them with explicit forms if it is possible to isolate yy and differentiate explicitly.

◇References & Navigation

CONFIRMATION // 理解度の確認

ACTIVE RECALL VERIFICATION

Select an answer to verify conceptual comprehension and reveal the technical rationale.

Q1

When differentiating an equation in xx and yy implicitly with respect to xx, what is ddx[y3]\frac{d}{dx}[y^3]?

Q2

Find dydx\frac{dy}{dx} for the circle x2+y2=25x^2 + y^2 = 25.

Q3

When differentiating the product term x2yx^2 y with respect to xx, which expression is obtained?

Q4

Find the slope of the tangent line to the curve x2+xy+y2=7x^2 + xy + y^2 = 7 at the point (1,2)(1, 2).

Q5

Why is implicit differentiation necessary for curves such as the Folium of Descartes (x3+y3=6xyx^3 + y^3 = 6xy)?