4x^3+27/16=0
x^3=-27/64
x=-3/4
2(x-2)^3=6又3/4
(x-2)^3=27/8
x-2=3/2
x=2+3/2
x=3.5
2x^2-18=0
x^2=9
x=3或x=-3
(2x-1)^2=√81
（2x-1）^2=9
2x-1=3 或2x-1=-3
2x=4 或 2x=-2
x=2或x=-1