bicuspide, cartesiana

(x^2 - k^2)*(x -k)^2 + (y^2 -k^2)^2 = 0

k = -2 (slider from -2 to 2, step 0.1)
a: (x^(2) - k^(2)) * (x - k)^(2) + (y^(2) - k^(2))^(2) = 0