How do you integrate int (x^2-1)/((x)*(x^2+1)) using partial fractions?

1 Answer
Oct 18, 2016

=ln((x^2+1)/x)+C

Explanation:

(x^2-1)/(x(x^2+1))=A/x+(Bx+C)/(x^2+1)
Developing
(x^2-1)/(x(x^2+1))=(A(x^2+1)+ x(Bx+C))/(x(x^2+1)
So we can compare the coefficients
x^2-1=A(x^2+1)+ x(Bx+C)
For x^2 , 1=A+B and -1=A and 0=C
Hence A=-1and B=2
int((x^2-1)dx)/(x(x^2+1))=intAdx/x+int((Bx+C)dx)/(x^2+1)
=int(-1dx)/x+int((2x)dx)/(x^2+1
=-lnx +ln(x^2+1)+C
=ln((x^2+1)/x)+C