x^2+4x+4=2

       (x+2)^2=2

               x+2=±√2

               x1=√2-2,x2=-√2-2

2.x^2-2x+1=4

          (x-1)^2=4

          x-1=±2

          x1=3,x2=-1

3.x^2-3x+4/9-4/9-1=0

          (x-2/3)^2=13/9

          x-2/3=±√13/3

          x1=(√13+2）/3,x2=(2-√13)/3

4.x^2-1/2x-1/2=0

          x^2-1/2x+1/16-1/16-1/2=0

          (x-1/4)^2=9/16

          x-1/4=±3/4

          x1=1,x2=-1/2

5.3(x^2-2x+1-1)-1=0

          3(x-1)^2=4

          (x-1)^2=4/3

          x-1=±2√3/3

          x1=2√3/3+1,x2=1-2√3/3

6.x^2-5/2x-2=0

          x^2-5/2x+25/16-25/16-2=0

          (x-5/4)^2=57/16

          x-5/4=±√57/4

          x1=(√57+5)/4,x2=(5-√57)/4

x²-4x=0的解是x1=0,x2=4

x²-4=0的根是x1=2,x2=-2

9x²+_6x__+_1__=(_3x__+1)²

若y²+ay+36是一個完全平方公式,則a=±12