Can somebody help me integrate

r(t)=t/1+t^2

I use the substitution method

t(1+t^2)^-1

let 1+t^2=u

2tdt=du

dt=du/2t

hence putting in ques

r(t)=∫t/u^-1 du/2t

=1/2∫u^-1 du

=1/2u^0/0

which is not possible .Any help?

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- Dec 11th 2009, 11:44 AMmathcalculushelpIntergral problem solving
Can somebody help me integrate

r(t)=t/1+t^2

I use the substitution method

t(1+t^2)^-1

let 1+t^2=u

2tdt=du

dt=du/2t

hence putting in ques

r(t)=∫t/u^-1 du/2t

=1/2∫u^-1 du

=1/2u^0/0

which is not possible .Any help? - Dec 11th 2009, 11:52 AMchisigma
What is the derivative of $\displaystyle 1+t^{2}$?... the answer is also the solution of integral (Wink) ...

http://digilander.libero.it/luposabatini/notte1.jpg

Merry Christmas from Italy

$\displaystyle \chi$ $\displaystyle \sigma$ - Dec 11th 2009, 12:51 PMmathcalculushelpthe derivative
the derivative is 2tdt .But I did this at the top and I end up with some other number.

- Dec 11th 2009, 01:56 PMDefunkt
Well, what's $\displaystyle \int \frac{1}{x}dx$ ?