A curve is given by x2+xy+y2=3x^2 + xy + y^2 = 3x2+xy+y2=3. Find the second derivative d2ydx2\frac{d^2y}{dx^2}dx2d2y at the point (1,1)(1, 1)(1,1).
-8/27
-1/3
-4/9
0