只需要求出相应点的斜率即可,也就是dy/dx的值
F[x_, y_] := x^2 + y^2 - (2 x^2 + 2 y^2 - x)^2;
Fx = D[F[x, y], x];
Fy = D[F[x, y], y];
那么,-Fx/Fy=(-2 x + 2 (-1 + 4 x) (-x + 2 x^2 + 2 y^2))/(2 y - 8 y (-x + 2 x^2 + 2 y^2))
把x=0,y=1/2代入,就得到了斜率!
Mathematica作图代码:
ContourPlot[
x^2 + y^2 == (2 x^2 + 2 y^2 - x)^2, {x, -.5, 1}, {y, -1, 1},
PlotRange -> Automatic]