✔ 最佳答案
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圖片參考:
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2009-05-21 18:18:16 補充:
利用積分代入法(integration by substitution)
2009-05-21 20:40:36 補充:
答案應是 1/6 cos^3(2x) - 1/2 cos2x + c, 有筆誤