What Substitution Should Be Used to Solve ∫(1+x)/(1+x^2) dx?

In summary, the conversation discusses the use of substitution in solving the integral ∫(1+x)/(1+x^2) dx. The participants mention trying different substitutions such as u = 1+ x, u = 1 + x^2, x, and x^2, but none of them work. They then suggest splitting the integral into two parts and using different substitutions for each part, with one being a trigonometric substitution and the other not. In the end, they come to the conclusion that using partial fractions or polynomial long division may be helpful in solving the integral.
  • #1
Miike012
1,009
0
∫(1+x)/(1+x^2) dx = ...

I have tryed multiple time using u substitution letting u = 1+ x... 1 + x^2... x ..x^2 but I can't get any of them to work.
 
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  • #2
Not surprising. Split the integral up into 1/(1+x^2) and x/(1+x^2). You need a different substitution for each part. One is a trig sub. The other isn't. They are different.
 
  • #3
is it u = 1+x^2 and u = arctan(x)?
 
  • #4
got it thank you.
 
  • #5
With a problem like that, either use partial fractions (if numerator power is lesser) or use polynomial long division (and then partial fractions on the remainder, if needed.)

It's always been beneficial to me.
 

FAQ: What Substitution Should Be Used to Solve ∫(1+x)/(1+x^2) dx?

What is the concept of integral using substitution?

The concept of integral using substitution is a method used to simplify and solve integrals by substituting a variable with another expression. This allows for a more manageable integral that can be easily solved using basic integration techniques.

When should I use substitution to solve an integral?

Substitution is most useful when the integrand (the expression inside the integral) contains a complicated or nested function. By substituting a variable with a simpler expression, the integral can be simplified and solved more easily.

How do I choose the substitution variable?

The substitution variable should be chosen in a way that will make the integral easier to solve. This often involves choosing a variable that will cancel out or simplify parts of the integrand, such as using u to replace sin x or ex.

Are there any general rules for substitution in integrals?

Yes, there are some general rules that can be followed when using substitution in integrals. These include substituting for a term with a power, substituting for a trigonometric function, and using parentheses when needed to avoid errors.

Can substitution be used for all types of integrals?

No, substitution is not always applicable to all integrals. It is most effective for integrals with a single variable and can also be used for definite integrals. However, it may not work for integrals with multiple variables or improper integrals.

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