計算題（每題10分）必須列出過程,否則不予計分  二、 Sketch the graph of y=x4-4x3 + 10, identify the extrema points and inflection points.

9„ A store can sell 20 bicycles per week at a price $400. each. The manager estimates that for each $10 price reduction she can sell two more bicycles per week. The bicycles cost the store $200 each. Find the price of the bicycles and quantity that maximize profit?____