Question

Express f(x) =3\x²- 1 in partial fraction​

Answer 1

3/(x ² - 1) = 3/((x - 1) (x + 1)) = a/(x - 1) + b/(x + 1)

==>   3 = a (x + 1) + b (x - 1)

==>   3 = (a + b) x + a - b

==>   a + b = 3 and a - b = 0

==>   a = b

==>   a + b = 2a = 3   ==>   a = 2/3 and b = 2/3

So you have

3/(x ² - 1) = 2/(3(x - 1)) + 2/(3(x + 1))