Math Problem Statement

Evaluate the integral: ∫ e^(8x) sin(e^(4x)) dx

Solution

The integral to be evaluated from the image is:

e8xsin(e4x)dx\int e^{8x} \sin(e^{4x}) \, dx

This is a challenging integral that likely requires a substitution and possibly integration by parts. Here's how to approach it:

Step 1: Substitution

Let: u=e4xu = e^{4x} Then, the derivative of uu with respect to xx is: du=4e4xdxdu = 4e^{4x} dx Or equivalently: dx=du4udx = \frac{du}{4u}

Now, substitute into the integral: e8xsin(e4x)dx=u2sin(u)du4u=14usin(u)du\int e^{8x} \sin(e^{4x}) dx = \int u^2 \sin(u) \frac{du}{4u} = \frac{1}{4} \int u \sin(u) du

Step 2: Integration by Parts

Use integration by parts, where:

  • Let v=uv = u, so that dv=dudv = du.
  • Let dw=sin(u)dudw = \sin(u) du, so that w=cos(u)w = -\cos(u).

Now, apply the integration by parts formula: vdw=vwwdv\int v dw = v w - \int w dv This gives: 14usin(u)du=14(ucos(u)+cos(u)du)\frac{1}{4} \int u \sin(u) du = \frac{1}{4} \left( -u \cos(u) + \int \cos(u) du \right) The integral of cos(u)\cos(u) is sin(u)\sin(u), so: 14(ucos(u)+sin(u))\frac{1}{4} \left( -u \cos(u) + \sin(u) \right)

Step 3: Substitute Back u=e4xu = e^{4x}

Finally, substitute back u=e4xu = e^{4x} into the result: 14(e4xcos(e4x)+sin(e4x))+C\frac{1}{4} \left( -e^{4x} \cos(e^{4x}) + \sin(e^{4x}) \right) + C

Thus, the evaluated integral is: 14(e4xcos(e4x)+sin(e4x))+C\boxed{\frac{1}{4} \left( -e^{4x} \cos(e^{4x}) + \sin(e^{4x}) \right) + C}

Would you like further clarification on any steps, or do you have any additional questions?


Here are five related questions you might explore:

  1. How does the substitution method simplify more complex integrals?
  2. Can you explain why integration by parts is useful for products of functions?
  3. What happens when the integral involves a product of an exponential and a trigonometric function?
  4. How can you apply substitution when dealing with different powers of exponential functions?
  5. What are common techniques to solve integrals involving sine or cosine with exponential terms?

Tip: When facing complex integrals, always check if substitution or integration by parts can simplify the process!

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Math Problem Analysis

Mathematical Concepts

Integration by Parts
Substitution
Exponential Functions
Trigonometric Functions

Formulas

Substitution: u = e^(4x), du = 4e^(4x) dx
Integration by Parts Formula: ∫v dw = v w - ∫w dv

Theorems

Integration by Parts Theorem
Substitution Method for Integrals

Suitable Grade Level

College Level