Question 1027550
Use implicit differentiation.

==> {{{4x^3+ 4y^3*(dy/dx) = 0}}}
==> {{{x^3+ y^3*(dy/dx) = 0}}} ==> {{{-x^3/y^3=dy/dx}}}

Differentiate again:

{{{3x^2+3y^2(dy/dx)(dy/dx) + y^3(d^2y/dx^2) = 0}}}

==> {{{-3x^2-3y^2(dy/dx)^2 = y^3(d^2y/dx^2)}}}

==> {{{(-3x^2)/y^3-(3(dy/dx)^2)/y = d^2y/dx^2}}}

==> {{{(-3x^2)/y^3-(3(-x^3/y^3)^2)/y = d^2y/dx^2}}}

==> {{{(-3x^2(y^4+x^4))/y^7 = d^2y/dx^2}}}

==>  {{{(-3x^2*25)/y^7 = d^2y/dx^2}}}

==>  {{{(-75x^2)/y^7 = d^2y/dx^2}}}