Accedmychevron_right11thchevron_rightmathchevron_rightPartial Fractionschevron_rightExercise 5.1

Solution

Let:

3x2+4x5(x1)3=Ax1+B(x1)2+C(x1)3\frac{3x^2+4x-5}{(x-1)^3}=\frac{A}{x-1}+\frac{B}{(x-1)^2}+\frac{C}{(x-1)^3}

Multiply by (x1)3(x-1)^3:

3x2+4x5=A(x1)2+B(x1)+C3x^2+4x-5=A(x-1)^2+B(x-1)+C

Solving gives:

A=3,B=10,C=2A=3,\quad B=10,\quad C=2

Hence:

3x2+4x5(x1)3=3x1+10(x1)2+2(x1)3\boxed{\frac{3x^2+4x-5}{(x-1)^3}=\frac{3}{x-1}+\frac{10}{(x-1)^2}+\frac{2}{(x-1)^3}}