急~請問獨占市場的彈性 - 經濟

老師給的投影片上面是這樣寫：
Note that a monopolist always produces a quantity at which
demand is elastic. If the firm produced a quantity for which
demand was inelastic, then if the firm raised its price,
quantity would fall by a smaller percentage than the rise in
price, so revenue would increase. Because costs would decrease
at a lower quantity, the firm would have higher revenue and
lower costs, so profit would be higher.

我不懂的是
明明說獨占廠商總是在彈性的時候製造，那後面又說
若demand是非彈性的時候，提高價格，收入又會增加
既然如此，為什麼不在非彈性的時候製造呢？
後面又有說成本在較少量的時候會減少，通常不是
製造越多成本越低嗎？
還是這有錯誤？
我整個霧煞煞啊T^T
請救救我！

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