Answer
$81x^8y^{4}$
Work Step by Step
RECALL:
(i) The products-to-powers rule states that: $(ab)^n=a^nb^n$
(ii) The power rule states that $(a^m)^n=a^{mn}$
Use the products-to-powers rule to find:
$=3^4(x^2)^4y^4
\\=81(x^2)^4y^4$
Use the power rule to find:
$=81x^{2(4)}y^4
\\=81x^8y^{4}$