Ta có : \(\frac{3\left(x^2+x-3\right)}{x^2+x-2}+\frac{x+3}{x+2}-\frac{x-2}{x-1}\)
\(=\frac{3\left(x^2+x-3\right)+\left(x+3\right)\left(x-1\right)-\left(x-2\right)\left(x-2\right)}{x^2+x-2}\)
\(=\frac{3x^2+3x-9+x^2+2x-3-x^2+4x-4}{x^2+x-2}\)
\(=\frac{3x^2+9x-16}{x^2+x-2}\)