Math Problem Statement

y is an implicit function of x. Find an expression for dy/dx. 4x^2y^3=ye^2x

Solution

We are given the equation 4x2y3=ye2x4x^2 y^3 = y e^{2x}, and we need to find an expression for dydx\frac{dy}{dx}, the derivative of yy with respect to xx. This involves implicit differentiation since yy is an implicit function of xx.

Step 1: Differentiate both sides with respect to xx

Left-hand side:

ddx(4x2y3)=4ddx(x2y3)\frac{d}{dx}(4x^2 y^3) = 4 \cdot \frac{d}{dx}(x^2 y^3) Using the product rule ddx(uv)=uv+uv\frac{d}{dx}(uv) = u'v + uv', where u=x2u = x^2 and v=y3v = y^3, we get: =4(2xy3+x23y2dydx)= 4 \left( 2x \cdot y^3 + x^2 \cdot 3y^2 \frac{dy}{dx} \right) Simplifying this: =8xy3+12x2y2dydx= 8x y^3 + 12x^2 y^2 \frac{dy}{dx}

Right-hand side:

ddx(ye2x)=ddx(y)e2x+yddx(e2x)\frac{d}{dx}(y e^{2x}) = \frac{d}{dx}(y) \cdot e^{2x} + y \cdot \frac{d}{dx}(e^{2x}) Using the chain rule for e2xe^{2x}: =dydxe2x+y2e2x= \frac{dy}{dx} e^{2x} + y \cdot 2e^{2x}

Step 2: Combine and solve for dydx\frac{dy}{dx}

Now, equate the differentiated sides: 8xy3+12x2y2dydx=dydxe2x+2ye2x8x y^3 + 12x^2 y^2 \frac{dy}{dx} = \frac{dy}{dx} e^{2x} + 2y e^{2x}

Rearrange the terms to isolate dydx\frac{dy}{dx}: 12x2y2dydxdydxe2x=2ye2x8xy312x^2 y^2 \frac{dy}{dx} - \frac{dy}{dx} e^{2x} = 2y e^{2x} - 8x y^3 Factor out dydx\frac{dy}{dx} on the left-hand side: dydx(12x2y2e2x)=2ye2x8xy3\frac{dy}{dx} (12x^2 y^2 - e^{2x}) = 2y e^{2x} - 8x y^3 Finally, solve for dydx\frac{dy}{dx}: dydx=2ye2x8xy312x2y2e2x\frac{dy}{dx} = \frac{2y e^{2x} - 8x y^3}{12x^2 y^2 - e^{2x}}

This is the expression for dydx\frac{dy}{dx}.

Would you like further details on this derivation or specific steps?

Here are 5 related questions to expand on this:

  1. How do you apply the product rule in differentiation?
  2. What are some key cases where implicit differentiation is essential?
  3. How does the chain rule work in this context?
  4. How does implicit differentiation differ from explicit differentiation?
  5. Why do we factor out dydx\frac{dy}{dx} when isolating it?

Tip: Implicit differentiation is particularly useful when dealing with equations where yy cannot be easily solved for xx, as it allows you to differentiate both sides of the equation with respect to xx directly.

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Math Problem Analysis

Mathematical Concepts

Implicit Differentiation
Product Rule
Chain Rule
Exponential Functions

Formulas

Product rule: d(uv)/dx = u'v + uv'
Chain rule: d(e^u)/dx = e^u * du/dx

Theorems

Implicit Differentiation

Suitable Grade Level

Grades 11-12