1. The problem statement, all variables and given/known data find d^2y/dx^2 at (1,1) for: x^2y + x^2 -y^2 = 1 2. Relevant equations none 3. The attempt at a solution i worked it all out but the answer im getting is not an option. could someone show me where i made a mistake? im not asking you to do the problem for me, just fix my error. this is what i did: first i found dy/dx: x^2(dy/dx) + y(2x) +2x -2y(dy/dx)=0 (x^2 - 2y)(dy/dx) = -2xy - 2x dy/dx = (-2xy-2x)/(x^2-2y) when i put (1,1) in, i got 4 then to find the second derivative i used the quotient rule: d^2y/dy^2 = [(x^2-2y) (-2x)(dy/dx) +y(-2) -2] - ((-2xy-2x)(2x-2)(dy/dx)]/(x^2-2y)^2 then i just put the values in. for the x's and y's i put in 1, and for dy/dx i put in 4. i ended up with: [(-1 x -2 x 4 + -2 -2) - (-2 -2) x (2-2(4) ] / 1 = 28 ? but this answer is incorrect. what did i do wrong? Thanks so much!