Ta có \(y=\log_3\left(\frac{x^2-2x+3}{x^2+2x+3}\right)=\log_3\left(x^2-2x+3\right)-\log_3\left(x^2+2x+3\right)\)
\(\Rightarrow y'=\frac{2x-2}{\left(x^2-2x+3\right)\ln3}-\frac{2x-2}{\left(x^2+2x+3\right)\ln3}=\frac{4x^2-12}{\left(x^4+2x^2+9\right)\ln3}\)