Đáp án:
$\begin{array}{l}
a)A = {\left( { - \frac{2}{3}x{y^3}} \right)^2}.{\left( {3x{y^2}} \right)^3}\\
= {\left( { - \frac{2}{3}} \right)^2}.{x^2}.{y^{3.2}}{.3^3}.{x^3}.{y^{2.3}}\\
= \frac{4}{9}.{x^2}.{y^6}.27.{x^3}.{y^6}\\
= \frac{4}{9}.27.{x^2}.{x^3}.{y^6}.{y^6}\\
= 12.{x^5}.{y^{12}}\\
b)A = 12{x^5}{y^{12}}\\
\Rightarrow \left\{ \begin{array}{l}
\text{Hệ số}:12\\
Biến:{x^5}{y^{12}}\\
Bậc:17
\end{array} \right.\\
c)x = - 1;y = 1\\
\Rightarrow A = 12.{x^5}.{y^{12}}\\
= 12.{\left( { - 1} \right)^5}{.1^{12}}\\
= - 12
\end{array}$
