Math Problem Statement

1. (4 pts) Let R be a region in the first quadrant enclosed by the curves y = x^2, 8y = x^2, x = y^2, and 8x = y^2. Use change of variables technique to calculate the double integral of x/y over region R. 2. (3 pts) Let R be a region in the xy-plane enclosed by the ellipse x^2/a^2 + y^2/b^2 = 1. Consider the change of variables given by x = au cos(v), y = bu sin(v) with the ranges 0 ≤ u ≤ 1, 0 ≤ v ≤ 2π. Show that the Jacobian of the transformation is equal to abu.

Solution

Let's tackle the problems one at a time.

Problem G1 involves a region RR in the first quadrant, enclosed by the curves y=x2y = x^2, 8y=x28y = x^2, x=y2x = y^2, and 8x=y28x = y^2. To solve the integral RxydA\iint_R \frac{x}{y} \, dA, we are advised to use a change of variables technique. Analyzing the curves suggests a coordinate transformation based on symmetry or scaling factors.

Problem 2 describes a region RR in the xyxy-plane enclosed by an ellipse x2a2+y2b2=1\frac{x^2}{a^2} + \frac{y^2}{b^2} = 1. The problem introduces a transformation x=aucosvx = a u \cos v and y=businvy = b u \sin v with the ranges 0u10 \leq u \leq 1 and 0v2π0 \leq v \leq 2\pi. Your task here is to verify the Jacobian of the transformation, showing that it equals abuab u.

Would you like step-by-step solutions for each part?

Here are five questions for further exploration:

  1. How would you select a suitable variable transformation in Problem G1 if no hints were provided?
  2. Why is the polar coordinate transformation not directly applicable for an ellipse in Problem 2?
  3. What does the Jacobian represent in the context of area transformations?
  4. How does the change of variables affect the bounds of integration?
  5. Can you generalize this approach for any ellipse with different semi-major and semi-minor axes?

Tip: When working with transformations, always calculate the Jacobian determinant to adjust for area distortion in the new coordinates.

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Math Problem Analysis

Mathematical Concepts

Change of Variables
Double Integration
Jacobian Determinant
Ellipse
Coordinate Transformation

Formulas

Double Integral: \( \iint_R \frac{x}{y} \, dA \)
Ellipse Equation: \( \frac{x^2}{a^2} + \frac{y^2}{b^2} = 1 \)
Change of Variables: \( x = au \cos v, \; y = bu \sin v \)
Jacobian Determinant: \( \frac{\partial (x, y)}{\partial (u, v)} \)

Theorems

Change of Variables Theorem
Jacobian Determinant Formula

Suitable Grade Level

Undergraduate (Calculus III)