初二数学二次根式化简题

√27／4
=√(3*9/4)
=√3*√(3²/2²)
=(3/2)√3
√8／3
=√(24/9)
=√(6*4/9)
=√6*√(2²/3²)
=(2/3)√6
√49／18
=√(2*7²/6²)
=√2*√(7²/6²)
=(7/6)√2
√28／45
√12倍x的立方／y的立方
=√(3*2²*x²*xy/y的四次方)
=√(3xy)*√[2²*x²/(y²)²]
=(2|x|/y²)√(3xy)