可解此方程,x1,2=[-b±√(b^2-4ac)]/2a
由a+b+c=0得b=-(a+c),代入上式即得
x1,2=[(a+c)±√((a+c)^2-4ac)]/2a
=[(a+c)±√(a-c)^2]/2a
=[a+c)±(a-c)]/2a
=1或c/a