メモしとかないと忘れちゃうよね

-y^2+x^2=1
https://www.wolframalpha.com/input?i=-y%5E2%2Bx%5E2%3D1&lang=ja

y^2-2xy+x^2-2^0.5y-2^0.5x=0
https://www.wolframalpha.com/input?i=y%5E2-2xy%2Bx%5E2-2%5E0.5y-2%5E0.5x%3D0&lang=ja