用配方法解方程~~~··

2x^2-5x-1=0
2x^2-5x=1
x^2-5x/2=1/2
x^2-5x/2+25/16=1/2+25/16
(x-5/4)^2=33/16=(±√33/4)^2
x-5/4=±√33/4
x=(5+√33)/4,x=(5-√33)/4

2x^2-5x-1=0
2(x^2-5/2*x)=1
2[x^2-2*(5/4)*x+(5/4)^2-(5/4)^2]=1
(x-5/4)^2-25/16=1/2
(x-5/4)^2=33/16
x-5/4=(+/-)根号（33/16）=(+/-)根号（33）/4
x=[5+(+/-)根号33]/4

题目有问题