Math Problem Statement

Find a Trapezoid Rule approximation to Integral from 0 to 1 e Superscript x cubed Baseline dx∫01ex3dx using n=100 subintervals. Integral from 0 to 1 e Superscript x cubed Baseline dx∫01ex3dx

Solution

To find a Trapezoid Rule approximation for the integral of ex3e^{x^3} from 0 to 1 with n=100n = 100 subintervals, we can follow these steps:

Trapezoidal Rule Formula

The Trapezoidal Rule for approximating the definite integral abf(x)dx\int_a^b f(x) \, dx is given by:

Tn=h2[f(x0)+2f(x1)+2f(x2)++2f(xn1)+f(xn)]T_n = \frac{h}{2} \left[ f(x_0) + 2f(x_1) + 2f(x_2) + \cdots + 2f(x_{n-1}) + f(x_n) \right]

Where:

  • aa is the lower limit of integration (in this case, 0),
  • bb is the upper limit of integration (in this case, 1),
  • h=banh = \frac{b - a}{n} is the width of each subinterval,
  • xi=a+ihx_i = a + ih for i=0,1,2,,ni = 0, 1, 2, \dots, n.

In this case:

  • a=0a = 0, b=1b = 1,
  • n=100n = 100,
  • f(x)=ex3f(x) = e^{x^3}.

Step-by-Step Calculation:

  1. Calculate the step size hh:

h=10100=0.01h = \frac{1 - 0}{100} = 0.01

  1. Calculate the points x0,x1,,x100x_0, x_1, \dots, x_{100}:

xi=0+i0.01=0.01ifori=0,1,2,,100x_i = 0 + i \cdot 0.01 = 0.01i \quad \text{for} \quad i = 0, 1, 2, \dots, 100

  1. Compute the function values f(xi)=e(xi)3f(x_i) = e^{(x_i)^3} for i=0,1,2,,100i = 0, 1, 2, \dots, 100.

  2. Apply the Trapezoidal Rule formula:

T100=0.012[f(0)+2i=199f(xi)+f(1)]T_{100} = \frac{0.01}{2} \left[ f(0) + 2 \sum_{i=1}^{99} f(x_i) + f(1) \right]

Let me compute this.The Trapezoid Rule approximation for the integral 01ex3dx\int_0^1 e^{x^3} \, dx using n=100n = 100 subintervals is approximately:

T1001.34197T_{100} \approx 1.34197

Would you like more details on the steps, or do you have any further questions?

Here are five related questions to expand your understanding:

  1. How does the error in the Trapezoidal Rule decrease as we increase the number of subintervals?
  2. What is the actual value of the integral 01ex3dx\int_0^1 e^{x^3} \, dx?
  3. How would the result change if we used Simpson's Rule instead of the Trapezoidal Rule?
  4. Can the trapezoidal rule be used for improper integrals?
  5. How can you derive the error bound for the Trapezoidal Rule?

Tip: For functions that curve significantly between points, increasing the number of subintervals nn can greatly improve the accuracy of the Trapezoidal Rule approximation.

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Math Problem Analysis

Mathematical Concepts

Numerical Integration
Trapezoidal Rule
Exponential Functions

Formulas

T_n = (h/2) * [f(x_0) + 2 * sum(f(x_i)) + f(x_n)]
h = (b - a) / n

Theorems

Trapezoidal Rule Approximation

Suitable Grade Level

Undergraduate level (Calculus I or II)