[tex]1) 8a^2-2a(-a+a^3)=8a^2 +2a^2-2a^4=10a^2-2a^4\\2) (y-9)(3y-1)-(2y+1)(5y-7)=\\3y^2-y-27y+9-(10y^2-14y+5y-7)=\\3y^2-28y+9-10y^2+14y-5y+7=\\-7y^2-19y+16[/tex]