1. The problem statement, all variables and given/known data Find the equation of the tangent line to the graph of x^2 - xy + y^2 = 19 (where y=y(x)) at (3,-2). 2. Relevant equations 3. The attempt at a solution So, this is what I did: d/dx(x^2-xy+y^2) = (19)d/dx 2x*dx/dx-dy/dx+dy/dx+2y(dy/dx)=0 2x+2y(dy/dx)=0 And I am stuck, the answer to this question is: y+2=8/7(x-3) and I don't know how to get the slope.