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1、,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,極限概念與數(shù)列的極限,極限概念與數(shù)列的極限,劉海濱,極限概念與數(shù)列的極限,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,割之彌細(xì), 所失彌少,割 之又割,以至 于不可割,則 與圓合體而無(wú) 所失矣。,如果變量 X按照某一規(guī)律無(wú)限地接近一個(gè)常數(shù)C,則稱(chēng) C為 X的極限 。 記作 或,極限概念與數(shù)列的極限,定 性 描 述,limX=C XC,limX=C XC,,,,,,,,,limX=C XC,極限概念與數(shù)列的極
2、限,,,,,,,,,,24,12,6,3,極限概念與數(shù)列的極限,2.598076211353,3.000000000000,3.105828541230,3.132628613281,,數(shù)列極限的-N定義,極限概念與數(shù)列的極限,一般地,對(duì)于數(shù)列 an,如果存在一個(gè)常數(shù)A,無(wú)論預(yù)先指定多么小的正數(shù),都能在數(shù)列中找到一項(xiàng) a N ,使得這一項(xiàng)后面的所有項(xiàng)與A的差的絕對(duì)值都小于( 即當(dāng) nN 時(shí),|an-A|< 恒成立),就把常數(shù)A叫做數(shù)列 an的極限,記作 an=A。,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,極限概念與數(shù)列的極限,解:(1)這個(gè)數(shù)列的各項(xiàng)與1的差的絕對(duì)值
3、依次是 1,,(2),(4),(3),.,例1,極限概念與數(shù)列的極限,(1)就極限的全過(guò)程來(lái)說(shuō),必須具有絕對(duì)的任意性。,只有這樣,當(dāng)nN時(shí),不等式|an-A| 恒成立,才能表明數(shù)列an無(wú)限趨近于A。,(2)就極限的全過(guò)程的某一瞬間來(lái)說(shuō),又是具體給定的。,隨著取值的越來(lái)越小,表明數(shù)列an不斷趨近于A的無(wú)限過(guò)程。,(3)數(shù)列an的極限是A。,an可能比A小,無(wú)限趨近于A;,無(wú)限趨近于A;,an也可能時(shí)而小于A時(shí)而大于A,無(wú)限趨近于A...,an也可能比A大,,極限概念與數(shù)列的極限,判斷下列命題是否正確(正確的選,不正確的選):,(1)對(duì)于數(shù)列an,如果存在常數(shù)A,當(dāng)正數(shù)等于0.1,0.01,0.0
4、01時(shí),都能在數(shù)列中找到一項(xiàng) a N ,使得這一項(xiàng)后面的所有項(xiàng)與A的差的絕對(duì)值都小于 ,則A是數(shù)列an的極限.( ),(2)對(duì)于數(shù)列an,如果存在常數(shù)A,無(wú)論預(yù)先給定多么小的正數(shù),都能在數(shù)列中找到一項(xiàng) a N ,使得這一項(xiàng)后面的所有項(xiàng)都屬于開(kāi)區(qū)間(A-,A+),則A是數(shù)列an的極限...( ),(3) 如果數(shù)列 an的每一項(xiàng)都是A,那么數(shù)列an的極限是A。( ),(6)若數(shù)列的極限是A,則任意去掉或改變其中的有限項(xiàng)后,新數(shù)列的極限仍為A。.( ),(5) 如果數(shù)列 an的極限是A,那么對(duì)于預(yù)先給定的小正數(shù),在區(qū)間(A-,A+)內(nèi)一定有該數(shù)列的無(wú)窮多項(xiàng)。..( ),
5、,,,,,,,,,,,,極限概念與數(shù)列的極限,判斷下列命題是否正確(正確的選,不正確的選):,(1)對(duì)于數(shù)列an,如果存在常數(shù)A,當(dāng)正數(shù)等于0.1,0.01,0.001時(shí),都能在數(shù)列中找到一項(xiàng) a N ,使得這一項(xiàng)后面的所有項(xiàng)與A的差的絕對(duì)值都小于 ,則A是數(shù)列an的極限。.( ),(2)對(duì)于數(shù)列an,如果存在常數(shù)A,無(wú)論預(yù)先給定多么小的正數(shù),都能在數(shù)列中找到一項(xiàng) a N ,使得這一項(xiàng)后面的所有項(xiàng)都屬于開(kāi)區(qū)間(A-,A+),則A是數(shù)列an的極限。. ( ),(3) 如果數(shù)列 an的每一項(xiàng)都是A,那么數(shù)列an的極限是A。( ),(6)若數(shù)列的極限是A,則任意去掉或改變其中的有限
6、項(xiàng)后,新數(shù)列的極限仍為A。..( ),(5) 如果數(shù)列 an的極限是A,那么對(duì)于預(yù)先給定的小正數(shù),在區(qū)間(A-,A+)內(nèi)一定有該數(shù)列的無(wú)窮多項(xiàng)。..( ),,,,,,,,,,,,,極限概念與數(shù)列的極限,判斷下列命題是否正確(正確的選,不正確的選):,(1)對(duì)于數(shù)列an,如果存在常數(shù)A,當(dāng)正數(shù)等于0.1,0.01,0.001時(shí),都能在數(shù)列中找到一項(xiàng) a N ,使得這一項(xiàng)后面的所有項(xiàng)與A的差的絕對(duì)值都小于 ,則A是數(shù)列an的極限.( ),(2)對(duì)于數(shù)列an,如果存在常數(shù)A,無(wú)論預(yù)先給定多么小的正數(shù),都能在數(shù)列中找到一項(xiàng) a N ,使得這一項(xiàng)后面的所有項(xiàng)都屬于開(kāi)區(qū)間(A-,A+),
7、則A是數(shù)列an的極限...( ),(3) 如果數(shù)列 an的每一項(xiàng)都是A,那么數(shù)列an的極限是A.( ),(6)若數(shù)列的極限是A,則任意去掉或改變其中的有限項(xiàng)后,新數(shù)列的極限仍為A.( ),(5) 如果數(shù)列 an的極限是A,那么對(duì)于預(yù)先給定的小正數(shù),在區(qū)間(A-,A+)內(nèi)一定有該數(shù)列的無(wú)窮多項(xiàng)..( ),,,,,,,,,,,,,極限概念與數(shù)列的極限,判斷下列命題是否正確(正確的選,不正確的選):,(1)對(duì)于數(shù)列an,如果存在常數(shù)A,當(dāng)正數(shù)等于0.1,0.01,0.001時(shí),都能在數(shù)列中找到一項(xiàng) a N ,使得這一項(xiàng)后面的所有項(xiàng)與A的差的絕對(duì)值都小于 ,則A是數(shù)列an的極限
8、.( ),(2)對(duì)于數(shù)列an,如果存在常數(shù)A,無(wú)論預(yù)先給定多么小的正數(shù),都能在數(shù)列中找到一項(xiàng) a N ,使得這一項(xiàng)后面的所有項(xiàng)都屬于開(kāi)區(qū)間(A-,A+),則A是數(shù)列an的極限...( ),(3) 如果數(shù)列 an的每一項(xiàng)都是A,那么數(shù)列an的極限是A.( ),(6)若數(shù)列的極限是A,則任意去掉或改變其中的有限項(xiàng)后,新數(shù)列的極限仍為A.( ),(5) 如果數(shù)列 an的極限是A,那么對(duì)于預(yù)先給定的小正數(shù),在區(qū)間(A-,A+)內(nèi)一定有該數(shù)列的無(wú)窮多項(xiàng)..( ),,,,,,,,,,,,,極限概念與數(shù)列的極限,判斷下列命題是否正確(正確的選,不正確的選):,(1)對(duì)于數(shù)列an
9、,如果存在常數(shù)A,當(dāng)正數(shù)等于0.1,0.01,0.001時(shí),都能在數(shù)列中找到一項(xiàng) a N ,使得這一項(xiàng)后面的所有項(xiàng)與A的差的絕對(duì)值都小于 ,則A是數(shù)列an的極限.( ),(2)對(duì)于數(shù)列an,如果存在常數(shù)A,無(wú)論預(yù)先給定多么小的正數(shù),都能在數(shù)列中找到一項(xiàng) a N ,使得這一項(xiàng)后面的所有項(xiàng)都屬于開(kāi)區(qū)間(A-,A+),則A是數(shù)列an的極限...( ),(3) 如果數(shù)列 an的每一項(xiàng)都是A,那么數(shù)列an的極限是A.( ),(6)若數(shù)列的極限是A,則任意去掉或改變其中的有限項(xiàng)后,新數(shù)列的極限仍為A.( ),(5) 如果數(shù)列 an的極限是A,那么對(duì)于預(yù)先給定的小正數(shù),在區(qū)間(A-,
10、A+)內(nèi)一定有該數(shù)列的無(wú)窮多項(xiàng)..( ),,,,,,,,,,,,,極限概念與數(shù)列的極限,判斷下列命題是否正確(正確的選,不正確的選):,(1)對(duì)于數(shù)列an,如果存在常數(shù)A,當(dāng)正數(shù)等于0.1,0.01,0.001時(shí),都能在數(shù)列中找到一項(xiàng) a N ,使得這一項(xiàng)后面的所有項(xiàng)與A的差的絕對(duì)值都小于 ,則A是數(shù)列an的極限.( ),(2)對(duì)于數(shù)列an,如果存在常數(shù)A,無(wú)論預(yù)先給定多么小的正數(shù),都能在數(shù)列中找到一項(xiàng) a N ,使得這一項(xiàng)后面的所有項(xiàng)都屬于開(kāi)區(qū)間(A-,A+),則A是數(shù)列an的極限...( ),(3) 如果數(shù)列 an的每一項(xiàng)都是A,那么數(shù)列an的極限是A.( ),(6
11、)若數(shù)列的極限是A,則任意去掉或改變其中的有限項(xiàng)后,新數(shù)列的極限仍為A.( ),(5) 如果數(shù)列 an的極限是A,那么對(duì)于預(yù)先給定的小正數(shù),在區(qū)間(A-,A+)內(nèi)一定有該數(shù)列的無(wú)窮多項(xiàng)..( ),,,,,,,,,,,,,極限概念與數(shù)列的極限,判斷下列命題是否正確(正確的選,不正確的選):,(1)對(duì)于數(shù)列an,如果存在常數(shù)A,當(dāng)正數(shù)等于0.1,0.01,0.001時(shí),都能在數(shù)列中找到一項(xiàng) a N ,使得這一項(xiàng)后面的所有項(xiàng)與A的差的絕對(duì)值都小于 ,則A是數(shù)列an的極限.( ),(2)對(duì)于數(shù)列an,如果存在常數(shù)A,無(wú)論預(yù)先給定多么小的正數(shù),都能在數(shù)列中找到一項(xiàng) a N ,使得這一項(xiàng)后面的所有項(xiàng)都屬于開(kāi)區(qū)間(A-,A+),則A是數(shù)列an的極限...( ),(3) 如果數(shù)列 an的每一項(xiàng)都是A,那么數(shù)列an的極限是A.( ),(6)若數(shù)列的極限是A,則任意去掉或改變其中的有限項(xiàng)后,新數(shù)列的極限仍為A.( ),(5) 如果數(shù)列 an的極限是A,那么對(duì)于預(yù)先給定的小正數(shù),在區(qū)間(A-,A+)內(nèi)一定有該數(shù)列的無(wú)窮多項(xiàng)..( ),,,,,,,,,,,,,極限概念與數(shù)列的極限,本節(jié)課到此結(jié)束,謝謝大家!,