4. Упростите выражение 1/y - (y+8)/(16-y^2) - 2/(y-4)

$$ \frac{1}{y} - \frac{y+8}{16-y^2} - \frac{2}{y-4} = \frac{1}{y} + \frac{y+8}{y^2 - 16} - \frac{2}{y-4} = \frac{1}{y} + \frac{y+8}{(y-4)(y+4)} - \frac{2}{y-4} = \frac{(y-4)(y+4) + y(y+8) - 2y(y+4)}{y(y-4)(y+4)} = \frac{y^2 - 16 + y^2 + 8y - 2y^2 - 8y}{y(y-4)(y+4)} = \frac{-16}{y(y-4)(y+4)} = \frac{-16}{y(y^2-16)} $$.

Ответ: $$\frac{-16}{y(y^2-16)}$$