2x²-6x+1=0
2x²-6x+9/2=7/2
2(x²-3x+9/4)=7/2
2(x-3/2)²=7/2
(x-3/2)²=7/4
x-3/2=±√7/2
所以
x=(3±√7)/2
公式法啊?
a=2 b=-6 c=1
b²-4ac=36-8=28
x=[6±√28]/4
=(3±√7)/2