x²-4x+2=0

x²-4x+2=0
x²-4x+2=0

x²-4x+2=0
答：x²-4x+2=0
x²-4x+4=2
(x-2)²=2
两边开平方得：
x-2=±√2
x=2±√2

△=b²-4ac=(-4)²-4×1×2=8
x1=[-b+根号△]/2a=2+根号2
x2=[-b-根号△]/2a=2-根号2