Answer :
[tex]\bf \sqrt{40x^2y^6}\qquad \begin{cases} 40=&2\cdot 2\cdot 2\cdot 5\\ &2^2\cdot 10\\ y^6=&y^{3\cdot 2}\\ &(y^3)^2 \end{cases}\implies \sqrt{2^2\cdot 10x^2(y^3)^2}\implies 2xy^3\sqrt{10}[/tex]
[tex]\bf \sqrt{40x^2y^6}\qquad \begin{cases} 40=&2\cdot 2\cdot 2\cdot 5\\ &2^2\cdot 10\\ y^6=&y^{3\cdot 2}\\ &(y^3)^2 \end{cases}\implies \sqrt{2^2\cdot 10x^2(y^3)^2}\implies 2xy^3\sqrt{10}[/tex]