Math Problem Statement

Solve the double integral: ∫∫ x(x + y) dy dx over the region [0, 2] x [0, 2]

Solution

The given problem is a double integral, which appears to be of the form:

0202x(x+y)dydx\int_0^2 \int_0^2 x(x + y) \, dy \, dx

Let's solve this step-by-step.

Step 1: Integrate with respect to yy

The inner integral is: 02x(x+y)dy\int_0^2 x(x + y) \, dy

Since xx is a constant with respect to yy, we can distribute xx inside: 02(x2+xy)dy\int_0^2 (x^2 + xy) \, dy

Now, integrate term by term: 02x2dy+02xydy\int_0^2 x^2 \, dy + \int_0^2 xy \, dy

Step 2: Evaluate the inner integrals

  • For the first term: 02x2dy=x202dy=x2[y]02=x2(20)=2x2\int_0^2 x^2 \, dy = x^2 \int_0^2 \, dy = x^2 [y]_0^2 = x^2 (2 - 0) = 2x^2

  • For the second term: 02xydy=x02ydy=x[y22]02=x222=2x\int_0^2 xy \, dy = x \int_0^2 y \, dy = x \left[ \frac{y^2}{2} \right]_0^2 = x \cdot \frac{2^2}{2} = 2x

So, the result of the inner integral is: 02x(x+y)dy=2x2+2x\int_0^2 x(x + y) \, dy = 2x^2 + 2x

Step 3: Integrate with respect to xx

Now, evaluate the outer integral: 02(2x2+2x)dx\int_0^2 (2x^2 + 2x) \, dx

Integrate term by term: 022x2dx+022xdx\int_0^2 2x^2 \, dx + \int_0^2 2x \, dx

Step 4: Evaluate the outer integrals

  • For the first term: 022x2dx=202x2dx=2[x33]02=2233=163\int_0^2 2x^2 \, dx = 2 \int_0^2 x^2 \, dx = 2 \left[ \frac{x^3}{3} \right]_0^2 = 2 \cdot \frac{2^3}{3} = \frac{16}{3}

  • For the second term: 022xdx=2[x22]02=2222=4\int_0^2 2x \, dx = 2 \left[ \frac{x^2}{2} \right]_0^2 = 2 \cdot \frac{2^2}{2} = 4

Step 5: Combine the results

The final result of the double integral is: 0202x(x+y)dydx=163+4=283\int_0^2 \int_0^2 x(x + y) \, dy \, dx = \frac{16}{3} + 4 = \frac{28}{3}

So, the solution to the integral is 283\frac{28}{3}.

Would you like more details or have any questions?

Here are 5 related questions you might find interesting:

  1. How does the order of integration affect the result of a double integral?
  2. What is the geometric interpretation of a double integral over a region?
  3. How do you evaluate double integrals over non-rectangular regions?
  4. Can double integrals be used to find the volume under a surface?
  5. How does changing the limits of integration affect the integral result?

Tip: When solving double integrals, simplifying the inner integral first can make the problem much more manageable.

Ask a new question for Free

By Image

Drop file here or Click Here to upload

Math Problem Analysis

Mathematical Concepts

Calculus
Double Integrals
Multivariable Calculus

Formulas

∫∫ f(x, y) dy dx = ∫ ( ∫ f(x, y) dy ) dx
∫ x^n dx = (x^(n+1))/(n+1)
∫ y^n dy = (y^(n+1))/(n+1)

Theorems

Fundamental Theorem of Calculus
Iterated Integrals

Suitable Grade Level

Undergraduate Calculus