X^2-6X+4=0(x-3)^2=5所以X1=根号5+3 X2=-根号5+3
(x-2)(x-4)=4x²-6x+4=0(x-3)²=5x-3=±√5x=±√5+3即 x1=√5+3 x2=-√5+3
x²-6x+8=4x²-6x=-4x²-6x+9=-4+9(x-3)²=5x-3=±√5x=3-√5,x=3+√5