## Nanoman 2 years ago Partial fractions question: x^3 -------------------- x^2 + 36x + 324 I used polynomial long division on this, and got: x+ 36 + 972x + 1166 -------------- x^2 + 36x + 324 I've gotten to the point where the partial fraction is 972x + 1166 = Ax 18A + B. A = 972, but I can't find out what B is.

1. .Sam.

What I get is$x-36+\frac{972x+11664}{x^2+36x+324}$

2. Nanoman

ohhh....right. I had that down on paper but typed it wrong on here.

3. .Sam.

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4. hartnn

to find out B, you can put x=0 in 972x + 1166 = Ax 18A + B. and you already know A , so you'll get B

5. .Sam.

$x-36+\frac{972x+11664}{x^2+36x+324} \\ \\\frac{972x+11664}{(x+18)^2}=\frac{A}{(x+18)}+\frac{B}{(x+18)^2}$

6. .Sam.

$972x+11664=A(x+18)+B \\ \\$ When x=-18 B=-5832 When x=0 18A-5832=11664 A=972 $x-36+\frac{972x+11664}{x^2+36x+324} \\ \\\frac{972x+11664}{(x+18)^2}=\frac{972}{(x+18)}-\frac{5832}{(x+18)^2}$

7. Nanoman

Thanks Sam, I really appreciate it. I was trying to move the terms around to get the answer, but just plugging it in works well.

8. .Sam.

welcome :)