Is There a Way to Integrate ∫xarctanx dx Without Going Back into Arctanx?

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In summary, the formula for integrating arctan is ∫ arctan(x) dx = x * arctan(x) - 1/2 * ln(1+x^2) + C. To solve an arctan integration problem, you can use the formula or substitution. Trigonometric identities can also be used to simplify and solve these problems. Special cases for arctan integration include when the expression inside the function is a square root or a rational function. To check the correctness of an integration solution, you can differentiate it, use online calculators, or seek verification from a math tutor.
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Pyroadept
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Homework Statement


∫xarctanx dx


Homework Equations


d/dx (arctanx) = 1/(1 + x^2)
∫1/(1 + x^2) = arctanx
∫u dv = uv - ∫v du

The Attempt at a Solution


Hi everyone,

Here's what I've done so far:

Use integration by parts:
u = arctanx
du = 1/(1 + x^2) dx

dv = x dx
v = (1/2)x^2

∫u dv = uv - ∫v du
= arctanx(1/2)x^2 - (1/2)∫x^2/(1 + x^2) dx

But how do you integrate this new integral without going back into arctanx, in which case you'll be left with zero?

Thanks for any help
 
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  • #2
Long division. [tex]\frac{x^2}{1+x^2}=1-\frac{1}{1+x^2}[/tex]
 

Question 1: What is the formula for integrating arctan?

The formula for integrating arctan is: ∫ arctan(x) dx = x * arctan(x) - 1/2 * ln(1+x^2) + C

Question 2: How do I solve an arctan integration problem?

To solve an arctan integration problem, you can use the formula for integrating arctan or use substitution, where you substitute u = arctan(x) and dx = du / (1+x^2).

Question 3: Can I use trigonometric identities to solve arctan integration problems?

Yes, you can use trigonometric identities such as arctan(x) = arctan(1/x) + π/2 or arctan(x) = π/2 - arctan(1/x) to simplify and solve arctan integration problems.

Question 4: Are there any special cases for arctan integration?

Yes, there are some special cases for arctan integration, such as when the expression inside the arctan function is a square root or when it is a rational function. In these cases, additional techniques may be needed to solve the integration.

Question 5: How can I check if my arctan integration solution is correct?

You can check your solution by differentiating it and seeing if it matches the original function. You can also use online integration calculators or ask a math tutor for verification.

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