How do you integrate (5x^2+7x-4)/(x^3+4x^2) using partial fractions?

1 Answer
Nov 4, 2016

The answer is =1/x+2lnx+3ln(x+4)+C

Explanation:

let's simplify the denominator x^3+4x^2=x^2(x+4)
So (x^2+7x-4)/(x^2(x+4))=A/x^2+B/x+C/(x+4)

:.5x^2+7x-4=A(x+4)+Bx(x+4)+Cx^2
-4=4A=> A=-1
coefficients of x, 7=A+4B=>B=2
Coefficients of x^2, 5=B+C=> C=3
:. int((x^2+7x-4)dx)/(x^2(x+4))=int-dx/x^2+int(2dx)/x+int(3dx)/(x+4)
=1/x+2lnx+3ln(x+4)+C