Expand your horizons with the diverse and informative answers found on IDNLearn.com. Our platform provides accurate, detailed responses to help you navigate any topic with ease.

Use (a) the Trapezoidal Rule, (b) the Midpoint Rule, and (c) Simpson's Rule to approximate the given integral with the specified value of [tex]$n$[/tex]. (Round your answers to six decimal places.)

[tex]
\int_1^5 \frac{6 \cos (4 x)}{x} \, dx, \quad n=4
[/tex]

(a) the Trapezoidal Rule
[tex]\square[/tex]

(b) the Midpoint Rule
[tex]\square[/tex]

(c) Simpson's Rule
[tex]\square[/tex]


Sagot :

To approximate the given integral
[tex]\[ \int_1^5 \frac{6 \cos (4 x)}{x} \, dx \][/tex]
using the specified methods (a) the Trapezoidal Rule, (b) the Midpoint Rule, and (c) Simpson's Rule with [tex]\( n = 4 \)[/tex], we can follow these steps.

### (a) The Trapezoidal Rule
1. Divide the interval [tex]\([1, 5]\)[/tex] into [tex]\( n = 4 \)[/tex] subintervals. So, the width of each subinterval [tex]\( h \)[/tex] is given by:
[tex]\[ h = \frac{b - a}{n} = \frac{5 - 1}{4} = 1 \][/tex]

2. Determine the partition points [tex]\( x_i \)[/tex] for [tex]\( i = 0 \)[/tex] to [tex]\( n \)[/tex]:
[tex]\[ x_0 = 1, \quad x_1 = 2, \quad x_2 = 3, \quad x_3 = 4, \quad x_4 = 5 \][/tex]

3. Compute the value of the function at each partition point:
[tex]\[ f(x) = \frac{6 \cos (4 x)}{x} \][/tex]

4. Apply the Trapezoidal Rule formula:
[tex]\[ \int_1^5 \frac{6 \cos (4 x)}{x} \, dx \approx \frac{h}{2} \left[ f(x_0) + 2 \sum_{i=1}^{n-1} f(x_i) + f(x_n) \right] \][/tex]

5. The approximate value using the Trapezoidal Rule to six decimal places is:
[tex]\[ -1.901363 \][/tex]

### (b) The Midpoint Rule
1. Divide the interval [tex]\([1, 5]\)[/tex] into [tex]\( n = 4 \)[/tex] subintervals, and the width of each subinterval [tex]\( h \)[/tex] remains:
[tex]\[ h = 1 \][/tex]

2. Determine the midpoint of each subinterval:
[tex]\[ x_{0.5} = 1.5, \quad x_{1.5} = 2.5, \quad x_{2.5} = 3.5, \quad x_{3.5} = 4.5 \][/tex]

3. Compute the value of the function at each midpoint:
[tex]\[ f(x) = \frac{6 \cos (4 x)}{x} \][/tex]

4. Apply the Midpoint Rule formula:
[tex]\[ \int_1^5 \frac{6 \cos (4 x)}{x} \, dx \approx h \sum_{i=1}^{n} f\left( x_{i - 0.5} \right) \][/tex]

5. The approximate value using the Midpoint Rule to six decimal places is:
[tex]\[ 2.941738 \][/tex]

### (c) Simpson's Rule
1. Divide the interval [tex]\([1, 5]\)[/tex] into [tex]\( n = 4 \)[/tex] subintervals of equal width [tex]\( h \)[/tex]:
[tex]\[ h = 1 \][/tex]

2. Compute the value of the function at the partition points and midpoints for alternating coefficients:
[tex]\[ f(x) = \frac{6 \cos (4 x)}{x} \][/tex]

3. Apply Simpson's Rule formula:
[tex]\[ \int_1^5 \frac{6 \cos (4 x)}{x} \, dx \approx \frac{h}{3} \left[ f(x_0) + 4 \sum_{i=1, 3, 5, \cdots} f(x_i) + 2 \sum_{i=2, 4, 6, \cdots (n-2)} f(x_i) + f(x_n) \right] \][/tex]

4. The approximate value using Simpson's Rule to six decimal places is:
[tex]\[ 1.327371 \][/tex]

### Summary of results:
- Trapezoidal Rule: [tex]\(-1.901363\)[/tex]
- Midpoint Rule: [tex]\(2.941738\)[/tex]
- Simpson's Rule: [tex]\(1.327371\)[/tex]