Integration by substitution
By Anonymous on Sunday, September 3,
2000 - 02:55 pm :
Hi
How do you go about integrating equations like
x/((x-1)2 )
By Chi Kin Ho (P1942) on Sunday,
September 3, 2000 - 05:35 pm :
Hi,
I believe I can help on this one, if the Nrich team do not
mind...
This is called integration by substitution, and you can find it
in most A-level textbooks. It goes like this:
If you substitute u=x-1,
then x=u+1
and du/dx=1, du=dx.
Thus, òx/(x-1)2 dx can be written as
ò(u+1)/u2 du
=ò1/u du+ò1/u2 du
=ln(u)+u-1/(-1)
=ln(u)-1/u
=ln(x-1)-1/(x-1)+c
Hope this helps.
Cheers,
Chi Kin Ho
By Tim Garton (P2843) on Sunday,
September 3, 2000 - 08:55 pm :
thanks