A curve has equation $$\(y=x^{n}+q x^{2}+9 x\)$$ ． $$\(\frac{\mathrm{d} y}{\mathrm{~d} x}=3 x^{2}-12 x+9\)$$ （b）Work out the coordinates of the turning points of the curve． ［4］

Answer:

Knowledge points:

Solution: