f(x) = (x)/[(x^2 + 4)]

Locate all inflection points

I got f'(x) = (-x^2 + 4)/[(x^2 +4)]^2

and found f''(x) = [2x(x^4 - 8x^2 - 48)]/[(x^2+4)^4]

x = 0, 4i, some other number

I'm sure theres an easier way of finding the second derivative, any help guys?