How do you express (2x - 1) / [(x - 1)^3 (x - 2)]2x1(x1)3(x2) in partial fractions?

1 Answer
Dec 20, 2016

The answer is =-1/(x-1)^3-3/(x-1)^2-3/(x-1)+3/(x-2)=1(x1)33(x1)23x1+3x2

Explanation:

Let's do the decomposition into partial fractions

(2x-1)/((x-1)^3(x-2))=A/(x-1)^3+B/(x-1)^2+C/(x-1)+D/(x-2)2x1(x1)3(x2)=A(x1)3+B(x1)2+Cx1+Dx2

=(A(x-2)+B(x-2)(x-1)+C(x-2)(x-1)^2+D(x-1)^3)/((x-1)^3(x-2))=A(x2)+B(x2)(x1)+C(x2)(x1)2+D(x1)3(x1)3(x2)

Therefore,

2x-1=A(x-2)+B(x-2)(x-1)+C(x-2)(x-1)^2+D(x-1)^32x1=A(x2)+B(x2)(x1)+C(x2)(x1)2+D(x1)3

Let x=2x=2, =>, 3=D3=D

Let x=1x=1, =>, 1=-A1=A

Coefficients of x^3x3, =>, 0=C+D0=C+D, =>, C=-3C=3

Let x=0x=0, =>,-1=-2A+2B-2C-D1=2A+2B2CD

-1=2+2B+6-31=2+2B+63

2B=-1-2-3=-62B=123=6, =>, B=-3B=3

Therefore,

(2x-1)/((x-1)^3(x-2))=-1/(x-1)^3-3/(x-1)^2-3/(x-1)+3/(x-2)2x1(x1)3(x2)=1(x1)33(x1)23x1+3x2