find the stationary point for $\displaystyle f(x,y) =x^4 +64y^4-2(x+8y)^2$
i got my fx =3x^3 -4x-32y
and fy= 256y^3-32x-256y
I don't know how to get the three points....any one can highlight to me??
Hello,
fx would rather be $\displaystyle 4x^3-\dots$
Stationary points are points (x,y) where $\displaystyle \frac{\partial f}{\partial x}=0$ and $\displaystyle \frac{\partial f}{\partial y}=0$
So solve for x and y in
$\displaystyle \bigg\{ \begin{array}{ccc} 4x^3-4x-32y & = & 0 \\ 256y^3-32x-256y & = & 0 \end{array}$