1.(3x+1)(3x-1)=3
9x^2 -1=3
9X^2=4
x^2=4/9
x=2/3
2.√(x-1)=x-1
x-1=(x-1)^2
x-1=x^2-2x+1
x^2-3x+2=0
(x-1)(x-2)=0
x=1 or x=2
3.请补充完整该题