Math Problem Statement

Change the order of integration for the double integral: \( \int_{-5}^{5} \int_{x^2}^{25} f(x,y) \, dy \, dx \)

Solution

The image presents a double integral transformation, where the order of integration is being swapped from 55x225f(x,y)dydx\int_{-5}^{5} \int_{x^2}^{25} f(x,y) \, dy \, dx to a different set of limits for integration in terms of dxdydx \, dy.

Let's break down the problem and solve it:

Initial Integral Setup:

55x225f(x,y)dydx\int_{-5}^{5} \int_{x^2}^{25} f(x,y) \, dy \, dx This is the double integral in the order dydxdy \, dx, with the limits:

  • For xx, the limits are x=5x = -5 to x=5x = 5.
  • For yy, the limits are y=x2y = x^2 to y=25y = 25.

Changing the Order of Integration:

  1. Interpret the Region of Integration:

    • The variable yy ranges from x2x^2 to 25, which means yx2y \geq x^2, so yy starts at the parabola y=x2y = x^2 and goes up to the constant value 25.
    • The variable xx ranges from 5-5 to 55.

    We need to understand this region in the xyxy-plane:

    • For yy, the lowest point occurs at y=0y = 0 (the vertex of the parabola y=x2y = x^2 when x=0x = 0).
    • For y=25y = 25, x225x^2 \leq 25, so xx ranges from 25=5-\sqrt{25} = -5 to 25=5\sqrt{25} = 5.
  2. New Limits for dxdydx \, dy Order:

    • The limits for yy are now from 00 to 2525.
    • For each fixed yy, xx ranges from y-\sqrt{y} to y\sqrt{y} (since y=x2y = x^2).

Transformed Integral:

Thus, the new integral with the order of integration swapped becomes: 025yyf(x,y)dxdy\int_{0}^{25} \int_{-\sqrt{y}}^{\sqrt{y}} f(x,y) \, dx \, dy

This is the correct transformation of the original integral.


Would you like more detailed explanations or have any questions on how the integration limits were determined?

Here are five follow-up questions related to this concept:

  1. How do we change the limits of integration for more complex regions?
  2. What types of functions benefit from swapping the order of integration?
  3. How does the shape of the region affect the integration process?
  4. Could we use polar coordinates to simplify a similar problem?
  5. Why is it important to graph the region when switching the order of integration?

Tip: Always sketch the region of integration when switching the order, as it helps to visualize the boundaries clearly.

Ask a new question for Free

By Image

Drop file here or Click Here to upload

Math Problem Analysis

Mathematical Concepts

Calculus
Double Integrals
Changing the Order of Integration

Formulas

Original Integral: \( \int_{-5}^{5} \int_{x^2}^{25} f(x,y) \, dy \, dx \)
Transformed Integral: \( \int_{0}^{25} \int_{-\sqrt{y}}^{\sqrt{y}} f(x,y) \, dx \, dy \)

Theorems

Fubini's Theorem

Suitable Grade Level

Undergraduate