∵xy≥0,5x³﹥0
∴x﹥0,y≥0
原式=5√(xy)÷√(5x³)
=5√(xy÷5x³)
=5√(xy×1/5x³)
=5√(y/5x²)
=5√[5y×(1/5x)²]
=5√(5y)/5x
=√(5y)/x