Explanation
Step 1
apply distributive property
[tex]\begin{gathered} (a^2+4a-6)(3a^2-a+3)= \\ a^2(3a^2-a+3)+4a(3a^2-a+3)-6(3a^2-a+3)= \\ 3a^4-a^3+3a^2+12a^3-4a^2+12a-18a^2+6a-18 \\ \end{gathered}[/tex]Step 2
add similar terms
[tex]\begin{gathered} 3a^4-a^3+3a^2+12a^3-4a^2+12a-18a^2+6a-18 \\ 3a^4+11a^3+-19a^2+18a-18 \\ \end{gathered}[/tex]I hope this helps you