describe the error sadie Made. and how to find the correct answerdescribe

Given the expression :
[tex]\sqrt[]{54a^7b^3}[/tex]The answer will be as following:
[tex]\begin{gathered} 54=9\cdot6=3^2\cdot6 \\ a^7=a^6\cdot a=(a^3)^2\cdot a \\ b^3=b^2\cdot b \\ \\ \sqrt[]{54a^7b^3}=\sqrt[]{3^2\cdot6\cdot(a^3)^2\cdot a\cdot b^2\cdot b}=3a^3b\sqrt[]{6ab} \end{gathered}[/tex]So, the error of Sadie is that: she didn't take the square root of a^5