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Resolve into partial fractions $\frac{3 x+2}{(x+1)\left(x^{2}-1\right)}$
1 Answer
| written 6.3 years ago by |
Solution:
$\frac{3 x+2}{(x+1)^{2}(x-1)}=\frac{A}{x+1}+\frac{B}{(x+1)^{2}}+\frac{C}{x-1}$
$\therefore 3 x+2=A(x-1)(x+1)+B(x-1)+C(x+1)^{2}$
$put x = -1$
$\therefore -3 + 2 = B(-1-1)$
$B = \frac{1}{2}$
$put x = 1$
$\therefore 3 + 2 = C (1+1^{2})$
$C = \frac{5}{4}$
$Put x = 0,B = \frac{1}{2}, C = \frac{5}{4}$
$\therefore 2=A(0-1)(0+1)+\frac{1}{2}(0-1)+\frac{5}{4}(0+1)^{2}$
$A = -\frac{5}{4}$
$\therefore \frac{3 x+2}{(x+1)^{2}(x-1)}=\frac{-\frac{5}{4}}{x+1}+\frac{\frac{1}{2}}{(x+1)^{2}}+\frac{\frac{5}{4}}{x-1}$