Evaluate the given integral by changing to polar coordinates. Sk (4x - y) dA, where R is the region in the first quadrant enclosed by the circle x² + y² = 4 and the lines x = 0 and y = x

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### Evaluating Integrals Using Polar Coordinates

In this exercise, we are asked to evaluate the given integral by changing to polar coordinates.

#### Given Integral
\[ \iint_{R} (4x - y) \, dA \]

where \( R \) is the region in the first quadrant enclosed by:
- The circle \( x^2 + y^2 = 4 \)
- The lines \( x = 0 \) and \( y = x \)

### Steps to Convert to Polar Coordinates

1. **Identify the region \( R \)**:
   - The region \( R \) is bounded by the circle of radius 2, i.e., \( x^2 + y^2 = 4 \).
   - The line \( y = x \), which forms a 45-degree angle (\( \frac{\pi}{4} \) radians) with the x-axis.
   - The line \( x = 0 \).

2. **Set up the polar coordinates**:
   - In polar coordinates, \( x = r \cos \theta \) and \( y = r \sin \theta \).
   - The differential area element \( dA \) in polar coordinates is \( r \, dr \, d\theta \).

3. **Determine the limits of integration**:
   - \( r \) ranges from 0 to the radius of the circle 2.
   - \( \theta \) ranges from 0 to \( \frac{\pi}{4} \).

4. **Convert the integrand**:
   - The integrand \( 4x - y \) in polar coordinates becomes \( 4(r \cos \theta) - (r \sin \theta) \).
   - This simplifies to \( r(4 \cos \theta - \sin \theta) \).

5. **Set up the integral in polar coordinates**:
   \[ \iint_{R} (4x - y) \, dA = \int_{0}^{\frac{\pi}{4}} \int_{0}^{2} r(4 \cos \theta - \sin \theta) \, r \, dr \, d\theta \]

6. **Evaluate the integral**:
   
   First, evaluate the inner integral with respect to \( r \):
   \[ \int_{0}^{2} r^2 (4 \cos \theta - \sin
Transcribed Image Text:### Evaluating Integrals Using Polar Coordinates In this exercise, we are asked to evaluate the given integral by changing to polar coordinates. #### Given Integral \[ \iint_{R} (4x - y) \, dA \] where \( R \) is the region in the first quadrant enclosed by: - The circle \( x^2 + y^2 = 4 \) - The lines \( x = 0 \) and \( y = x \) ### Steps to Convert to Polar Coordinates 1. **Identify the region \( R \)**: - The region \( R \) is bounded by the circle of radius 2, i.e., \( x^2 + y^2 = 4 \). - The line \( y = x \), which forms a 45-degree angle (\( \frac{\pi}{4} \) radians) with the x-axis. - The line \( x = 0 \). 2. **Set up the polar coordinates**: - In polar coordinates, \( x = r \cos \theta \) and \( y = r \sin \theta \). - The differential area element \( dA \) in polar coordinates is \( r \, dr \, d\theta \). 3. **Determine the limits of integration**: - \( r \) ranges from 0 to the radius of the circle 2. - \( \theta \) ranges from 0 to \( \frac{\pi}{4} \). 4. **Convert the integrand**: - The integrand \( 4x - y \) in polar coordinates becomes \( 4(r \cos \theta) - (r \sin \theta) \). - This simplifies to \( r(4 \cos \theta - \sin \theta) \). 5. **Set up the integral in polar coordinates**: \[ \iint_{R} (4x - y) \, dA = \int_{0}^{\frac{\pi}{4}} \int_{0}^{2} r(4 \cos \theta - \sin \theta) \, r \, dr \, d\theta \] 6. **Evaluate the integral**: First, evaluate the inner integral with respect to \( r \): \[ \int_{0}^{2} r^2 (4 \cos \theta - \sin
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