Представьте в виде многочлена выражение: (0.2a^2+3b^3)(0.2a^2-3b^3)

Решите задачу:

$0.2a^2(0.2a^2-3b^3)+3b^3(0.2a^2-3b^3)$
$0.2a^2(0.2a^2)+0.2a^2(-3b^3)+3b^3(0.2a^2-3b^3)$
$0.2a^2(0.2a^2)+0.2a^2(-3b^3)+(3b^3(0.2a^2)+3b^3(-3b^3))$
$0.2a^2(0.2a^2)+0.2a^2(-3b^3)+3b^3(0.2a^2)+3b^3(-3b^3)$
$0.04a^4-0.6a^2b^3+0.6b^3a^2-9b^6$
$0.04a^4+0a^2b^3-9b^6$
$0.04a^4+0b^3-9b^6$
$0.04a^4+0-9b^6$
$0.04a^4-9b^6$
$-9b^6+0.04a^4$