# Partial fractions

1. Sep 24, 2009

### pillar

1/(x+5)^2 (x-1)
B=(-1/6) C=(1/36)

I can't find the value of A, what method do you use to find it?

2. Sep 24, 2009

### rl.bhat

b]1/(x+5)^2 (x-1)[/b] = A/(x+5) + B/(x + 5)^2 + C/(x - 1)
Put x = 0.

3. Sep 24, 2009

### tanujkush

$$\frac{1}{(x+5)^{2}(x-1)}$$ will disintegrate into $$\frac{Ax+B}{(x+5)^{2}} + \frac{C}{x-1}$$

Compare coefficients on both sides to get

A = -1/36
B = -11/36
C = 1/36

4. Sep 24, 2009

### pillar

$$\frac{(x)^3}{(x+4)^{2}}$$ will disintegrate into $$x+4$$=$$\frac{Ax+B}{(x+4)^{2}}$$

I'm not sure where to go from there, to get the values of A & B.

5. Sep 25, 2009

### tanujkush

$$\frac{(x)^3}{(x+4)^{2}}$$ will disintegrate into

$$\frac{(x+4-4)^3}{(x+4)^2}$$

which you can expand using the [tex](a+b)^3[\tex\ standard formula and then its the same as the last one. Compare coefficients of powers of x on both sides to get A,B,C and so on.