Làm tính nhâna) x2 (5x3 – x – 6)                  &

* Hướng dẫn giải

a)x² (5x³ – x – 6) = x² .5x³ – x².x – x².6

                              =    5x⁵ – x³ – 6x²

b) ( x² -2xy + y² ).( x – y ) = x.( x² -2xy + y² ) – y.( x² -2xy + y²)

                                       = x³ – 3x²y + 3xy² – y³