1) ...........=2/3 a^6 b³ - a^4 b^5
2) ........=a³b^7 + 3/4 a^4 b^4
3) ........= - (11/7 a³x³ - 11/4 a²x³ - 11ax^4)*28/11 ax^6= - 4a^4 x^9 + 7a³x^9 + 28a²x^(10)
4) ........= - ( - 22/9 b^6 y+11/5 b³y² - 11by^5)*45/22 b^4 y^5= 5b^(10)y^6 - 4.5b^7 y^7 + 22.5b^5 y^(10)