根号18除于根号8
=3√2/2√2
=3/2
4根号15除于2根号5
=2√3
根号1又3分之2除于根号6分之5
=√[(5/3)/(5/6)]
=√2
2根号X2平方Y除于3根号XY=?
=[2√(x²y/xy)]/3
=2√x/3