(40分!!!!)1條數學問題......唔該幫下手!!!

(√125 / 6) - (8/√45)
= [(√(5³)/ 6 ] - {8 /[ 3√[(3²)(5)] ]}
= [(5√5)/ 6 ] - [8 /(3√5)]
= [(5√5)/ 6 ] - {[8(√5)] / [(3√5)(√5)]}
= [(5√5)/ 6 ] - {[8(√5)] / 15}
= {[(5√5)(5)]/ [(6)(5)]} - {[8(√5)(2)] / [(15)(2)]}
= [(25√5) - (16√5)] / 30
= (9√5) / 30
= (3√5) / 10

√125 / 6 - 8√45
= ( 5√5 ) / 6 - 24√5
= (5√5 - 144√5 ) / 6
= -139√5 / 6