-3x²+4x+2=0
3x²-4x=2
3(x²-4x/3)=2
x²-4x/3=2/3
(x²-4x/3+4/9)=2/3+4/9
(x-2/3)²=10/9
x-2/3=±√10/3
x=(2+√10)/3 或x=(2-√10)/3