Integrating $\int\arctan 4t \,dt$ - Integration by Parts

  • Thread starter tandoorichicken
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In summary, to integrate $\int\arctan 4t \,dt$ using integration by parts, we need to identify $u = \arctan 4t$ and $dv = dt$ and use the integration by parts formula. The purpose of integration by parts is to find the integral of a product of two functions. The steps for using integration by parts are: identifying $u$ and $dv$, finding $du$ and $v$, and substituting into the formula. Some common mistakes include solving for the wrong integral, not simplifying, and choosing $u$ and $dv$ incorrectly. Integration by parts cannot be used for all integrals, and there may be more efficient methods to solve certain integr
  • #1
tandoorichicken
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How does one integrate
[tex]\int\arctan 4t\,dt[/tex]
?

This is out of a section on integration by parts. Maybe that would help but I don't see any "parts." I only see one, the arctan.
 
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  • #2
Let u = arctan4t
dv = dt
 
  • #3
Thank you so much. Please tell me if I did this correctly.
Integration by Parts:
[tex]\int u\,dv = uv - \int v\,du [/tex]

[itex]u = \arctan 4t , \,dv = dt , v = t\,dt , \,du = \frac{4}{16t^2 + 1}[/itex]
[tex]\int\arctan 4t\,dt = t\arctan 4t - \int\frac{4t}{16t^2 + 1}\,dt = t\arctan 4t - \frac{1}{8}\ln(16t^2 + 1) + C [/tex]
 
  • #4
yup! looks good to me!
 

1. How do I approach integrating $\int\arctan 4t \,dt$ using integration by parts?

To integrate this expression, we need to use the integration by parts formula, which states: $\int u\, dv = uv - \int v\, du$. Here, we can let $u = \arctan 4t$ and $dv = dt$. We can then use the derivative of $u$ and the integral of $dv$ to find the integral of $\arctan 4t$.

2. What is the purpose of using integration by parts?

Integration by parts is a method used to find the integral of a product of two functions. It is helpful when the integrand cannot be easily integrated using other methods, such as substitution or trigonometric identities.

3. What are the steps for using integration by parts?

The steps for using integration by parts are:

  • Identify the function to be integrated, which we will call $u$.
  • Identify the function to be differentiated, which we will call $dv$.
  • Find the derivative of $u$, which we will call $du$.
  • Find the integral of $dv$, which we will call $v$.
  • Substitute these values into the integration by parts formula: $\int u\, dv = uv - \int v\, du$.
  • Solve for the integral on the right-hand side of the equation using known integration techniques.

4. What are some common mistakes when using integration by parts?

Some common mistakes when using integration by parts include:

  • Solving for the wrong integral on the right-hand side of the equation.
  • Not simplifying the integral on the right-hand side of the equation.
  • Forgetting to include a constant of integration when solving for the final integral.
  • Choosing $u$ and $dv$ incorrectly.
  • Forgetting to use the product rule when finding the derivative of $u$.

5. Can integration by parts be used to solve all integrals?

No, integration by parts can only be used to solve certain integrals. It is not always the most efficient method, and there are other integration techniques that may be more suitable for certain integrals.

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