Find all points where the tangent line is horizontal.
The equation is x^(2) + xy + y^(2) = 1
Okay so from a previous thread I learned that the horizontal tangent line is when a single point touches the equation and in this case the cirlce/oval.
I took the derivative and i got:
2x + xy' + y + 2y^(2) y' = 0
I'm looking at the graph of this and I think there are only two horizontal tangents but I dont know how to compute them. Please show me how. Thanks.