[tex]\cfrac{(21x^5y^8)^2}{3x^2}\implies \cfrac{((3)(7)x^5y^8)^2}{3x^2}\implies \cfrac{3^2\cdot 7^2x^{5\cdot 2}y^{8\cdot 2}}{3x^2}\implies \cfrac{3^2}{3}\cdot \cfrac{7^2 x^{10} y^{16}}{x^2} \\\\\\ 3\cdot 7^2 x^{10}\cdot x^{-2} y^{16}\implies 3\cdot 49x^{10-2}y^{16}\implies 147x^8y^{16}[/tex]
