What is the Integral of (2)/(x^2 + 1)?

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In summary, the integral of (2x)/(x^2 + 1) is ln|x^2 + 1| + C, and the integral of (2)/(x^2 + 1) is 2tan^-1(x) + C.
  • #1
ZedCar
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Homework Statement



Integrate (2x)/(x^2 + 1)

Homework Equations





The Attempt at a Solution



Is the answer:

(2x) log|x^2 + 1|

as I thought the answer to this type of question is the log of the absolute value of the denominator multiplied by the numerator.

The answer given when I use Wolfram Alpha is log(x^2+1) + (tan x)^-1
 
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  • #2
Actually your answer would be ln(x2+1)+C. (look at putting t=x2+1)

Which is what wolfram gave to me.
 
  • #3
Thank you.
Yes, I'm getting the same answer as you now on Wolfram.

If the question had instead been
Integrate (2)/(x^2 + 1) (no x in the numerator)

Would the answer also have been log|x^2 + 1| + c
 
  • #4
Oh, it's ok, I've just realized I can't do that.
 
  • #5
ZedCar said:
Thank you.
Yes, I'm getting the same answer as you now on Wolfram.

If the question had instead been
Integrate (2)/(x^2 + 1) (no x in the numerator)

Would the answer also have been log|x^2 + 1| + c

In that case the answer would be 2tan-1(x) + C since d/dx(tan-1x) = 1/(x2+1).
 

Related to What is the Integral of (2)/(x^2 + 1)?

1. What is the integral of (2x)/(x^2 + 1)?

The integral of (2x)/(x^2 + 1) is ln(x^2 + 1) + C, where C is the constant of integration.

2. How do you solve the integral of (2x)/(x^2 + 1)?

To solve this integral, you can use the substitution method by letting u = x^2 + 1. Then, du/dx = 2x and the integral becomes ∫(2x)/(x^2 + 1) dx = ∫(1/u) du = ln(u) + C = ln(x^2 + 1) + C.

3. What is the domain of the function (2x)/(x^2 + 1)?

The domain of this function is all real numbers, as the denominator x^2 + 1 is always positive and does not equal to 0 for any real value of x.

4. Can this integral be solved using any other method?

Yes, this integral can also be solved using the partial fractions method by breaking down the function into simpler fractions and then integrating each term separately. However, the substitution method is often easier and more efficient for this particular integral.

5. Is the integral of (2x)/(x^2 + 1) a definite or indefinite integral?

Since this integral does not have any specified limits of integration, it is considered an indefinite integral. This means that the result is a function, rather than a specific numerical value.

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