integration problem .. (1 Viewer)

[Mathematician]

integrate x^2/(x+1)
.

when u do it by substitution using u=x+1 and hence converting x^2 to (u-1)^2 and changing du to dx you get -3/2 in the final result.

changing the integral to [(x+1)(x-1) +1]/(x+1) and integrating it this way you get a similar result without the -3/2.

my question is, is the -3/2 in the answer with the first method just part of the constant of the answer ??

 

[wogboy]

Yeah, if you get a constant in your final answer when finding indefinite intergrals by integrating by substitution, just ignore any constants that may come up in the answer (in this case 3/2), and don't forget to put a +C as usual.

 

[Mathematician]

k..

k cool thanx.

 

[Mathematician]

....

And with definte integrals the -3/2 gets taken off anyway ( when finding the value).

( if u used substitution)