Сократите дробь: (9-x^2)/(15-2x-x^2).

Ответ:

\[15 - 2x - x^{2} = 0\]

\[x^{2} + 2x - 15 = 0\]

\[x_{1} + x_{2} = - 2,\ \ \]

\[x_{1} \cdot x_{2} = - 15\]

\[\Longrightarrow x_{1} = - 5;\ \ x_{2} = 3.\]

\[15 - 2x - x^{2} =\]

\[= - (x + 5)(x - 3) =\]

\[= (3 - x)(x + 5).\]