x²+根号下y-2=2x-1
x²-2x+1+根号下y-2=0
（x-1)^2 +√(y-2) =0
x-1=0 ,y-2=0
x=1,y=2
代入a²x²-4ay=0
a^2-8a=0 ,a(a-8)=0,a=0或a=8