Given:
[tex]\sqrt[]{18x^4y^5}[/tex]The expansion is,
[tex]\sqrt[]{18x^4y^5}=\sqrt[]{2\times3\times3\times x\times x\times x\times x\times y\times y\times y\times y\times y}[/tex]On simplification we get,
[tex]\begin{gathered} =\sqrt[]{2\times3^2\times x^2\times x^2\times y^2\times y^2\times y} \\ =3x^2y^2\sqrt[]{2y} \end{gathered}[/tex]Hence, Leslie was correct.