Thực hiện phép tính: f) (x − 2)/( x + 1) : (x^2 − 5x + 6)/( x^2 − 2x − 3) .

f) \(\frac{{x - 2}}{{x + 1}}:\frac{{{x^2} - 5x + 6}}{{{x^2} - 2x - 3}} = \frac{{x - 2}}{{x + 1}} \cdot \frac{{{x^2} - 2x - 3}}{{{x^2} - 5x + 6}} = \frac{{x - 2}}{{x + 1}} \cdot \frac{{\left( {x + 1} \right)\left( {x - 3} \right)}}{{\left( {x - 2} \right)\left( {x - 3} \right)}} = 1.\)