a, \(\dfrac{\sqrt{63y^3}}{\sqrt{7y}}=\dfrac{3y\sqrt{7y}}{\sqrt{7y}}=3y\)
b, \(\dfrac{\sqrt{48x^3}}{\sqrt{3x^5}}=\dfrac{4x\sqrt{3x}}{x^2\sqrt{3x}}=\dfrac{4}{x}\)
c, \(\dfrac{\sqrt{45mn^2}}{\sqrt{20m}}=\dfrac{3n\sqrt{5m}}{2\sqrt{5m}}=\dfrac{3n}{2}\)
d, \(\dfrac{\sqrt{16a^4b^6}}{\sqrt{128a^6b^6}}=\dfrac{4a^2\left|b^3\right|}{8a^3\left|b^3\right|}=\dfrac{1}{2a}\)