2x^2-5x+2=0
(x-2)*(2x-1)=0
x1=2;x2=0.5
还挺麻烦呐!
x^2-5/2x=-1
x^2-5/2x+25/16=25/16-1
(x-5/4)^2=9/16
x1=5/4+3/4=2
x2=5/4-3/4=0.5
好了吧!