A curve has the equation x2+xy+2y2=14x^2 + xy + 2y^2 = 14x2+xy+2y2=14
The gradient of the tangent to the curve is −13\displaystyle -\frac{1}{3}−31 at the points A A\,A and BBB.
Show that 5x−y=05x - y = 05x−y=0 at A A\,A and BBB.
Find the coordinates of A A\,A and BBB.
