1. ## Complex Second derivative

$x^3 + y^3 = 6xy$

I have tried countless times to get to the proposed answer of $\frac{16xy}{(2x-y^2)^3}$ but my numerator never simplifies to 16xy. So if some one can show me how to do this I would really appreciate it.

Thank you

2. ## Re: Complex Second derivative

Originally Posted by sakonpure6
$x^3 + y^3 = 6xy$
We will assume that $y=f(x)$.
$3x^2+3y^2y'=6y+6xy'\\6x+6y(y')^2+3y^2y''=6y''+6y' +6xy''$