设x^2=y 则y^2-6y+9=0(y-3)^2=0y=3x^2=3x=根号3 x=-根号3希望能帮到你！
令y=x^2,则y^2-6y+9=0(y-3)^2=0y1=y2=3当y=3时x^2=3即 x=根号3 ，x=负根号3
