[tex]\displaystyle\bf\\-0,3a\cdot\Big(a^{2} -3\Big)\Big(a^{2}+3\Big)=-0,3a\cdot \Big[(a^{2})^{2} -3^{2} \Big] =-0,3a\cdot\Big(a^{4} -9\Big)=\\\\\\=-0,3a\cdot a^{4} -0,3a\cdot (-9)=-0,3a^{5} +2,7a[/tex]