A curve has equation y=x3−27xy = x^3 - 27xy=x3−27x.
The point AAA on the curve has xxx-coordinate 333.
The point BBB on the curve has xxx-coordinate 3+h3 + h3+h.
Show that the gradient of the line ABABAB is h2+9hh^2 + 9hh2+9h.
Explain how the result of part (a) can be used to show that AAA is a stationary point on the curve.
