1.√125 - √1/125 - √16 /5
=5√5-1/25√5-4/5√5
=√5(5-1/25-4/5)
=(104/25)√5
2.（√18 - √ 27 )÷√6 ＋ 8√1/2
=√3-3/2√2+4√2
=√3+(5/2)√2