Sửa đề thành rút gọn phân số nhé :
\(\frac{\left(\frac{x}{x+3+3}-\frac{x}{3.x^2+3x}+\frac{9}{x^2-9}\right):3}{x+3}\)
\(=\frac{\frac{x}{3\left(x+6\right)}-\frac{x}{9x^2+9x}+\frac{9}{\left(x^2-9\right).3}}{x+3}\)
\(=\frac{\frac{x}{3x+18}-9x-9+\frac{3}{x^2-9}}{x+3}\)
\(=\frac{\frac{x-9x\left(3x+18\right)}{3x+18}+\frac{3-9\left(x^2-9\right)}{x^2-9}}{x+3}\)
\(=\frac{\frac{x-27x^2-162x}{3x+18}+\frac{3-9x^2+81}{x^2-9}}{x+3}\)
\(=\frac{\frac{27x^2-161x}{3x+18}+\frac{-9x^2+84}{x^2-9}}{x+3}\)
\(=\frac{27x^2-161x}{\left(3x+18\right):\left(x+3\right)}+\frac{-9x^2+84}{\left(x^2-9\right):\left(x+3\right)}\)
Đến đây thì dễ r ha
