[微積] dx不是實數?
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最近在學習微積分時讀了一本介紹微積分史的書,其中在講到dx的時候給了dx的雙重性質
(1)某些時候,dx不等於0,因為它只是"很靠近"0
(2)某些時候,dx等於0,因為它無窮小
最後留下了問題
試證:dx不是實數
在這裡我思考了很久,感覺dx很實在啊!甚至知道它就是非常趨近於0的一個數
那為什麼不是實數呢?
另外,我知道證明一個數是不是有理數通常可以用 p/q pq屬於Z
那證明是不是實數要如何作呢?
ps.
原po目前高3,現在自學大一微積分,有哪裡觀念不對還請各位指導,謝謝
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※ 編輯: sk90040 (49.218.37.82), 04/02/2016 10:04:23
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