[tex]\dfrac{\sqrt{128x^{5}y^{6}}}{2x^{7}y^{5}}=\dfrac{\sqrt{2x\left(8x^{2}y^{3}\right)^{2}}}{2x^{7}y^{5}}\\\\=\dfrac{8x^{2}y^{3}}{2x^{7}y^{5}}\sqrt{2x}=\dfrac{4\sqrt{2x}}{x^{5}y^{2}}[/tex]
