Помогите упростить выражение: [latex] \frac{2}{ x^{2} -3x} - \frac{1}{ x^{2} +3x} - \frac{x+1}{ x^{2} -9} [/latex]

[latex] \frac{2}{x^2-3x}- \frac{1}{x^2+3x}- \frac{x+1}{x^2-9}=\\\\= \frac{2}{x(x-3)}- \frac{1}{x(x+3)}- \frac{x+1}{(x+3)(x-3)}=\\\\= \frac{2(x+3)-(x-3)-x(x+1)}{x(x+3)(x-3)}= \\\\= \frac{2x+6-x+3-x^2-x}{x(x-3)(x+3)}=\\\\= \frac{9-x^2}{x(x-3)(x+3)}= \frac{-(x^2-9)}{x(x^2-9)}=- \frac{1}{x} [/latex]