(1/2a)^2+x^2-ax=1/4a^2+1/2ay+1/9
1/4a^2+x^2-ax=1/4a^2+1/2ay+1/9
x^2-ax=1/2ay+1/9
x=1/3或-1/3
y2/3或-2/3
好巧,又是你