Answer :
[tex]\\ \tt\hookrightarrow (3a^2-2a)(-6a^5+10a^4+9a^3)[/tex]
[tex]\\ \tt\hookrightarrow 3a^2(-6a^5+10a^4+9a^3)-2a(-6a^5+10a^4+9a^3)[/tex]
[tex]\\ \tt\hookrightarrow -18a^7+30a^6+27a^5+12a^6-20a^5-18a^4[/tex]
[tex]\\ \tt\hookrightarrow -18a^7+42a^6+7a^5-18a^4[/tex]