1/4(3x+1)^2-4=0
1/4(3x+1)^2=4
(3x+1)^2=16
3x+1=4或3x+1=-4
x1=1,x2=-5/3
-2/3x^2+1/9=0
2/3x^2=1/9
x^2=1/6
x1=根号6/6,x2=-根号6/6