Math Problem Statement

Consider the transformation from Cartesian coordinates $(x,y)$ to parametric $(u,v)$ defined by the following: x = u³-3uv² y = 3u-v-v3 Calculate the Jacobian determinent $ J = \frac{\partial(x,y)}{\partial(u,v)) $, then evaluate the double integral over the region $D$ in the $uv$ plane definite by $u^2 + v^2 = 1$: 1= f (x²+y²) du dv D

Solution

Step 1: Calculate the Jacobian Determinant J=(x,y)(u,v)J = \frac{\partial(x, y)}{\partial(u, v)}

Given the transformation: x=u33uv2,y=3uvv3,x = u^3 - 3uv^2, \quad y = 3u - v - v^3, the Jacobian matrix is:

\begin{pmatrix} \frac{\partial x}{\partial u} & \frac{\partial x}{\partial v} \\ \frac{\partial y}{\partial u} & \frac{\partial y}{\partial v} \end{pmatrix}.$$ #### Compute the partial derivatives: 1. **Partial derivatives of $$x$$:** $$\frac{\partial x}{\partial u} = \frac{\partial}{\partial u}(u^3 - 3uv^2) = 3u^2 - 3v^2,$$ $$\frac{\partial x}{\partial v} = \frac{\partial}{\partial v}(u^3 - 3uv^2) = -6uv.$$ 2. **Partial derivatives of $$y$$:** $$\frac{\partial y}{\partial u} = \frac{\partial}{\partial u}(3u - v - v^3) = 3,$$ $$\frac{\partial y}{\partial v} = \frac{\partial}{\partial v}(3u - v - v^3) = -1 - 3v^2.$$ Thus, the **Jacobian matrix** is: $$J = \begin{pmatrix} 3u^2 - 3v^2 & -6uv \\ 3 & -1 - 3v^2 \end{pmatrix}.$$ #### Calculate the Jacobian Determinant: $$\det(J) = (3u^2 - 3v^2)(-1 - 3v^2) - (-6uv)(3).$$ Expanding: $$\det(J) = -3u^2 - 9u^2v^2 + 3v^2 + 9v^4 + 18uv = 3v^2 - 3u^2 + 9v^4 - 9u^2v^2 + 18uv.$$ --- ### Step 2: Set Up the Double Integral The integral is: $$\iint_D f(x^2 + y^2) \, du \, dv,$$ where $$D$$ is the region defined by $$u^2 + v^2 = 1$$. ---

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Math Problem Analysis

Mathematical Concepts

Multivariable Calculus
Jacobian Determinant
Double Integrals
Coordinate Transformations

Formulas

Jacobian Matrix: J = [∂x/∂u ∂x/∂v; ∂y/∂u ∂y/∂v]
Jacobian Determinant: det(J) = (∂x/∂u)(∂y/∂v) - (∂x/∂v)(∂y/∂u)
Double Integral: ∫∫_D f(x² + y²) du dv

Theorems

Change of Variables Theorem
Jacobian Determinant for Coordinate Transformations

Suitable Grade Level

Undergraduate