Tính \(\frac{{{x^6} - {y^6}}}{{{x^4} - {y^4} - {x^3}y + x{y^3}}}\).

Ta có:

\(\frac{{{x^6} - {y^6}}}{{{x^4} - {y^4} - {x^3}y + x{y^3}}}\)

\( = \frac{{{{\left( {{x^3}} \right)}^2} - {{\left( {{y^3}} \right)}^2}}}{{{x^3}(x - y) + {y^3}(x - y)}}\)

\( = \frac{{\left( {{x^3} + {y^3}} \right)\left( {{x^3} - {y^3}} \right)}}{{\left( {{x^3} + {y^3}} \right)(x - y)}}\)\( = \frac{{{x^3} - {y^3}}}{{x - y}}\)

\( = \frac{{\left( {x - y} \right)\left( {{x^2} + xy + {y^2}} \right)}}{{x - y}}\)\( = {x^2} + xy + {y^2}\)

Vậy \(\frac{{{x^6} - {y^6}}}{{{x^4} - {y^4} - {x^3}y + x{y^3}}} = {x^2} + xy + {y^2}\).