Find the product. \[ -9 x y^{5}\left(3 x y^{2}+9 x y-4 x\right) \] \[ -9 x y^{5}\left(3 x y^{2}+9 x y-4 x\right)=\square \] (Simplify your answer:)

Step 1 ：Define the expression as \(-9 x y^{5}\left(3 x y^{2}+9 x y-4 x\right)\)

Step 2 ：Simplify the expression to get \(x^{2} y^{5}\left(-27 y^{2}-81 y+36\right)\)

Step 3 ：So, the simplified form of \(-9 x y^{5}\left(3 x y^{2}+9 x y-4 x\right)\) is \(x^{2} y^{5}\left(-27 y^{2}-81 y+36\right)\)

Step 4 ：Hence, the final answer is \(\boxed{x^{2} y^{5}\left(-27 y^{2}-81 y+36\right)}\)