\(C=\frac{3x^2-x+2}{\left(x-1\right)\left(x+3\right)}-\frac{x}{x-1}-\frac{x-1}{x+3}\left(x\ne1;x\ne-3\right)\)
\(=\frac{3x^2-x+2}{\left(x-1\right)\left(x+3\right)}-\frac{x\left(x+3\right)}{\left(x-1\right)\left(x+3\right)}-\frac{\left(x-1\right)^2}{\left(x-1\right)\left(x+3\right)}\)
\(=\frac{3x^2-x+2}{\left(x-1\right)\left(x+3\right)}-\frac{x^2+3x}{\left(x-1\right)\left(x+3\right)}-\frac{x^2-2x+1}{\left(x-1\right)\left(x+3\right)}\)
\(=\frac{3x^2-x+2-x^2-3x-x^2+2x-1}{\left(x-1\right)\left(x+3\right)}\)
\(=\frac{x^2-2x+1}{\left(x-1\right)\left(x+3\right)}=\frac{\left(x-1\right)^2}{\left(x-1\right)\left(x+3\right)}=\frac{x-1}{x+3}\)
Vậy C=\(\frac{x-1}{x+3}\left(x\ne1;x\ne-3\right)\)
