解：原式?lim[(1?x??1?x)?x] ?lim?11(1?1?x)?x ?1e. x??例5 求lim(x??3?x2?x). 1x?2)x?22x解原式?lim[(1?x??](1?21x?2)?4 ?e2. 三、小结 1.两个准则 夹逼准则; 单调有界准则 . 2.两个重要极限 设?为某过程中的无穷小sin?, 110某过程lim??1; 20某过程lim(1??)??e. 思考题 求极限lim?3?9xx???x?1x 思考题解答 1xx???lim3?9?xx? ?lim?9x???x?13??x1??1??x?x?1? ?9?lim??1?x??x???3???3?????311xx?x ?9?e?9 0
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