Integration help, urgent.

[flibbage0]

If you have 2x/x^2+1 and you need to integrate it, why is it ln x^2+1 what happens to the 2x?

 

[The Halk]

I can't remember integration from school however I can remember it wasn't urgent.

 

[Freakbro]

I can't remember integration from school however I can remember it wasn't urgent.

Excellent answer

 

[T345]

What has numbers got to do with interrogation?

 

[JonJ678]

As written, the integral of 2x/x^2+1 is x+ 2log(x) + constant.

 

[lord filbuster]

Integrate by substitution. V=x^2+1. dV=2xdx. Therefore the original equation becomes dv/V, the integral of which is = ln(V) = ln (x^2+1) +c

 

[Amleto]

integrate f'(x)/f(x) dx = ln( f(x) ) + const

 

[Amleto]

ah, nm

 

[RomanNose]

The derivative of X^2+1=2x, you probably didn't spot that.
When you see a fraction, look for derivatives as it makes it much easier than substitution.
And good luck, please no annoying vector questions .

 

[lord filbuster]

ah, nm

Saw your edit, nm.

 

[flibbage0]

Thank you all for the quick replies, especially Amleto and RomanNose.

Makes sense now.

The derivative of X^2+1=2x, you probably didn't spot that.
When you see a fraction, look for derivatives as it makes it much easier than substitution.
And good luck, please no annoying vector questions .

Thanks good luck to you as well, I have a feeling it isn't going to go well for me but I've done my best.

 

[mufc802]

The derivative of X^2+1=2x, you probably didn't spot that.
When you see a fraction, look for derivatives as it makes it much easier than substitution.
And good luck, please no annoying vector questions .

This.

Make it the first thing you check in an integral question involving a fraction. I will probably forget to do this in the exam tomorrow.