Question

求这四道题的答案（二次根式）

过程哟谢谢！！

Answer 1

(27/5)√[(13²-12²)/27]
=(27/5)√[(13+12)(13-12)/27]
=(27/5)√(25/27)
=(27/5)√[(5/9)²×3]
=(27/5×5/9)√3
=3√3

(-abc/2)√[c³/(2a^4b)]
=(-abc/2)√{ [c/(2a²b)]²×2bc }
=(-abc/2)×c/(2a²b)×√(2bc)
=[-c²/(4a)]√(2bc)

5√(ab)×[-4√(a³b)] (a≥0, b≥0)
=5×(-4)×√(ab×a³b)
=-20×√(a^4b²)
=-20×√(a²b)²
=-20a²b

√(a³b^6)÷√(ab) (a﹥0, b﹥0)
=√(a³b^6÷ab)
=√(a²b^5)
=√[(ab²)²×b]
=ab²√b