2次根式啊 (1)根号24 乘 根号27 (2)根号6 乘 (-根号15) (3)根号18 乘 根号20 乘 根号75 (4)根号3² 乘

(1)√24*√27
=2√3*3√3
=6*√3*√3
=6*3
=18
(2)√6 * (-√15)
=-√6*√15
=-√2*√3*√3*√5
=-3√10
(3)√18*√20*√75
=3√2*2√5*5√3
=30√2*√5*√3
=30√30
(4)√3² 乘 4² 乘 5
=3*16*5
=240
二.
(1)√18/√8
=3√2/2√2
=3/2
(2)2倍根号5分之4倍根号15
=2√(4/5)*4√15
=2*2√(1/5)*4√15
=16√(1/5)*√5*√3
=16√3
(3)根号1又3分之2 除 根号6分之5
=√(5/3)/√(5/6)
=√(5/3)*√(6/5)
=√[(5/3)*(6/5)]
=√2
(4) 3倍根号xy分之2倍根号x²y
=2√x^2y/3√xy
=2x√xy/3√xy
=2x/3
三.化简.
(1)根号4乘49
=2*7
=14
(2) 根号300
=10√3
(3)根号49分之9
=3/7
(4)根号4c²分之a²b
=a√b/2c