√24×√216/√6+5
=2√6×6√6/√6+5
=12√6+5
64x³+729=0
(4x)³=-729
(4x)³=(-9)³
4x=-9
x=-9/4
（根号2-2根号3）²
=2-2√2*2√3+12
=14-4√6