Math Problem Statement

Find dy/dx by implicit differentiation for the equation 4x^3 + x^2y - xy^3 = 2

Solution

We are tasked with finding dydx\frac{dy}{dx} using implicit differentiation for the equation:

4x3+x2yxy3=24x^3 + x^2y - xy^3 = 2

Step-by-Step Implicit Differentiation:

  1. Differentiate each term with respect to xx while treating yy as a function of xx (i.e., apply the chain rule when differentiating terms involving yy).

First term: 4x34x^3

ddx[4x3]=12x2\frac{d}{dx}[4x^3] = 12x^2

Second term: x2yx^2y

We use the product rule for x2yx^2y, where x2x^2 is one function and yy is the other: [ \frac{d}{dx}[x^2y] = \frac{d}{dx}[x^2] \cdot y + x^2 \cdot \frac{dy}{dx} = 2xy + x^2\frac{dy}{dx} ]

Third term: xy3-xy^3

Again, apply the product rule for xy3xy^3, where xx is one function and y3y^3 is the other: [ \frac{d}{dx}[-xy^3] = -\left(\frac{d}{dx}[x] \cdot y^3 + x \cdot \frac{d}{dx}[y^3]\right) = -y^3 - 3xy^2\frac{dy}{dx} ]

Differentiate the right-hand side:

ddx[2]=0\frac{d}{dx}[2] = 0

Combine all the differentiated parts:

12x2+2xy+x2dydxy33xy2dydx=012x^2 + 2xy + x^2\frac{dy}{dx} - y^3 - 3xy^2\frac{dy}{dx} = 0

Isolate dydx\frac{dy}{dx}:

Group the terms involving dydx\frac{dy}{dx} on one side: x2dydx3xy2dydx=y312x22xyx^2\frac{dy}{dx} - 3xy^2\frac{dy}{dx} = y^3 - 12x^2 - 2xy

Factor out dydx\frac{dy}{dx}: dydx(x23xy2)=y312x22xy\frac{dy}{dx}(x^2 - 3xy^2) = y^3 - 12x^2 - 2xy

Solve for dydx\frac{dy}{dx}: dydx=y312x22xyx23xy2\frac{dy}{dx} = \frac{y^3 - 12x^2 - 2xy}{x^2 - 3xy^2}

Thus, the implicit derivative is: dydx=y312x22xyx23xy2\frac{dy}{dx} = \frac{y^3 - 12x^2 - 2xy}{x^2 - 3xy^2}

Would you like a detailed explanation of any step, or do you have any questions?

Here are 5 questions that expand on this topic:

  1. How does implicit differentiation differ from explicit differentiation?
  2. What is the product rule, and why is it used here?
  3. How would the result change if there were higher powers of yy involved?
  4. Can you apply implicit differentiation to trigonometric functions?
  5. How does this process extend to higher-order derivatives?

Tip: When applying the product rule in implicit differentiation, always remember to differentiate yy as a function of xx, which adds a dydx\frac{dy}{dx} term.

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Math Problem Analysis

Mathematical Concepts

Implicit Differentiation
Product Rule
Chain Rule

Formulas

Product Rule: d(uv)/dx = u'v + uv'
Chain Rule: d(y^n)/dx = n*y^(n-1) * dy/dx

Theorems

Implicit Differentiation Theorem

Suitable Grade Level

Grades 11-12