Решите уравнение: 6-x(x+1)=9-x^2.

\[6 - x(x + 1) = 9 - x^{2}\]

\[6 - x^{2} - x = 9 - x^{2}\]

\[- x = 9 - 6\]

\[- x = 3\]

\[x = - 3.\]