x^2+2x+2=8x+4
x^2-6x=2
x^2-6x+9=11
(x-3)^2=11
x=3+√11或x=3-√11
x^2-2x-4=0
x^2-2x=4
x^2-2x+1=5
(x-1)^2=5
x=1+√5或x=1-√5