6) Simplify the expression \( \frac{y^2 - 8y + 16}{16 - y^2} \).

\( \frac{y^2 - 8y + 16}{16 - y^2} = \frac{(y - 4)^2}{-(y - 4)(y + 4)} = \frac{-(y - 4)}{y + 4} \) (assuming \( y
eq \pm 4 \)).