maths
posted by chrystabelle on .
express x1/(x+1)(x2)^2 into partial fractions

let
(x1)/((x+1)(x2)^2) = A/(x1) + B/(x2) + C/(x2)^2
multiply both sides by (x+1)(x2)^2
A(x2)^2 + B(x2)(x+1) + C(x+1) = x1
let x = 2, > 3C = 1 or C=13
let x = 1 > 9A + 2 or A = 2/9
let x = 0 > 4A  2B + C = 1
4(2/9)  2B + 1/3 = 1
times 9
8  18B + 3 = 9
B = 2/9
so (x1)/(x2)^2 = 2/(9(x+1)) + 2/(9(x2)) + 1/(3(x2)^2)
verified with Wolfram:
http://www.wolframalpha.com/input/?i=%28x1%29%2F%28%28x%2B1%29%28x2%29%5E2%29 
in the middle of the solution above the line should read:
et x = 2, > 3C = 1 or C=1/3