Упростите выражение (1/(b-y)(y-5)-1/(b-y)(b-5)-1/(b-5)(y-5))*(b^2-9y^2)/(b^4+y^4).

\[= \frac{b - 5 - y + 5 - b + y}{(b - y)(y - 5)(b - 5)} =\]

\[= \frac{0}{(b - y)(y - 5)(b - 5)} = 0\]

\[2)\ 0 \cdot \frac{b^{2} - 9y^{2}}{b^{4} + y^{4}} = 0\]