Упрости выражение

\(\dfrac{1}{x(x-4)}+\dfrac{1}{(x-4)(x-8)}+\dfrac{1}{(x-8)(x-12)}+\dfrac{1}{(x-12)(x-16)}=\) [ \(\frac{4}{x(x-16)}\) | \(x+12\) | \(\frac{4}{x-16}\) | \(\frac {1}{x(x-12)}\) ]