Math Problem Statement

Evaluate \(\iint_{R} (4y - 1) \, dA\) where \(R = [0, 5] \times [0, 4]\)

Solution

The given problem asks to evaluate the double integral:

R(4y1)dA\iint_{R} (4y - 1) \, dA

where R=[0,5]×[0,4]R = [0, 5] \times [0, 4], meaning that xx ranges from 0 to 5 and yy ranges from 0 to 4.

We can solve this step-by-step.

Step 1: Set up the integral

The integral can be written as:

0504(4y1)dydx\int_0^5 \int_0^4 (4y - 1) \, dy \, dx

Step 2: Evaluate the inner integral

We first integrate with respect to yy:

04(4y1)dy=[2y2y]04\int_0^4 (4y - 1) \, dy = \left[ 2y^2 - y \right]_0^4

Now, evaluate this at the bounds y=4y = 4 and y=0y = 0:

(2(4)2(4))(2(0)2(0))=(2164)=324=28\left( 2(4)^2 - (4) \right) - \left( 2(0)^2 - (0) \right) = (2 \cdot 16 - 4) = 32 - 4 = 28

So, the result of the inner integral is 28.

Step 3: Evaluate the outer integral

Now we integrate with respect to xx:

0528dx=28x05=28(5)28(0)=140\int_0^5 28 \, dx = 28x \big|_0^5 = 28(5) - 28(0) = 140

Final Answer:

The value of the double integral is:

140\boxed{140}

Would you like further details or have any questions?

Related Questions:

  1. What is the geometrical interpretation of a double integral?
  2. How would the answer change if the function was different, such as (2y3)(2y - 3)?
  3. Can you evaluate the same integral over a different region, such as R=[1,4]×[0,3]R = [1, 4] \times [0, 3]?
  4. How does changing the limits of integration affect the solution?
  5. Can you perform the integration using polar coordinates for a circular region?

Tip:

When solving double integrals, always make sure to carefully choose the correct order of integration and verify the bounds for each variable.

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Math Problem Analysis

Mathematical Concepts

Double Integral
Multivariable Calculus
Integration over Rectangular Regions

Formulas

\(\iint_{R} f(x, y) \, dA = \int_a^b \int_c^d f(x, y) \, dy \, dx\)

Theorems

Fubini's Theorem

Suitable Grade Level

College Calculus