y=(a^(2/3)-x^(2/3))^(3/2)

y'=((a^(2/3)-x^(2/3))^(1/2))/(x^(1/3))

y=f'(x0)*(x-x0)+y0

при x0=0, y0=a; y=((a^(2/3)-x^(2/3))^(1/2))/(x^(1/3))*x+a
при y0=0, x0=a; y=((a^(2/3)-x^(2/3))^(1/2))/(x^(1/3))*(x+a)