½â·¨¶þ ÖùÃæ×ø±ê£¬Èçͼ
I???dxdy?2Dxy1x?y2(x2?y2)dz ¡¡¡3·Ö
11x?rcos?,y?rsin???2?0d??rdr?2r2dz ¡¡¡6·Ö
0r?2??r3(1?r2)dr?01?6 ¡¡¡8·Ö
Îå¡¢£¨±¾ÌâÂú·Ö10·Ö£©
ÒÑÖªLÊǵÚÒ»ÏóÏÞÖдӵã(0,0)ÑØÔ²ÖÜx2?y2?2xµ½µã(2,0)£¬ÔÙÑØÔ²ÖÜx2?y2?4µ½µã£¨ÀûÓøñÁÖ¹«Ê½¼ÆË㣩 (0,2)µÄÇúÏ߶Σ¬¼ÆËãÇúÏß»ý·ÖI??3x2ydx?(x3?x?2y)dy£®
L½â Èçͼ£¬
P?3x2y,Q?x3?x?2y£¬ÇÒ
?P?Q?3x2,?3x2?1£®Ôò ?y?x I??LPdx?Qdy???(D?Q?P?)dxdy ?x?y ?11?22 1dxdy???2???1???422DÁù¡¢£¨±¾ÌâÂú·Ö8·Ö£©
Éèf(u,v)¾ßÓÐÁ¬ÐøµÄÆ«µ¼Êý, w?f(xy,yz)£¬Ö¤Ã÷£º x?w?w?w?z?y£® ?x?z?yÖ¤Ã÷
?w?w?w?yf1',?xf1'?zf2',?yf2'£¬ ¡¡¡6·Ö ?x?y?zËùÒÔ µÈʽ×ó±ß ?x?w?w?w?z?xyf1'?yzfz'£¬µÈʽÓÒ±ßy?xyf1'?yzfz'£® ?x?z?y¹ÊµÈʽ³ÉÁ¢£® ¡¡¡8·Ö
Æß¡¢£¨±¾ÌâÂú·Ö14·Ö£©
£¨1£©ÒÑÖªÈý¸öÕýÊýÖ®ºÍΪa£¬ÊÔÎÊÕâÈý¸öÕýÊý·Ö±ðΪºÎֵʱ£¬ËüÃǵĵ¹ÊýÖ®»ý×îС£®
½â £¨1£©ÉèÈý¸öÕýÊý·Ö±ðΪx,y,z£¬ÔòÄ¿±êº¯Êý f(x,y,z)? ·½·¨Ò» »¯ÎªÎÞÌõ¼þ¼«Öµ
1£¬Ô¼ÊøÌõ¼þx?y?z?a£® xyzg(x,y)?11£¬x?0,y?0,x?y?a ?xy(a?x?y)axy?x2y?xy2ay?2xy?y2ax?2xy?x2Ôò gx??£¬gy??£¬ ¡¡¡4·Ö
[xy(a?x?y)]2[xy(a?x?y)]2aa,y?£® ¡¡¡6·Ö 33aaaÓÉʵ¼ÊÎÊÌâµÄÒâÒåÖª£¬x?,y?ʱ£¬g(x,y)È¡×îСֵ£¬´Ëʱz?£®
333a¼´Èý¸öÕýÊý·Ö±ðΪx?y?z?ʱ£¬ËüÃǵĵ¹ÊýÖ®»ý×îС£® ¡¡¡7·Ö
3·½·¨¶þ ÎÊÌâµÈ¼ÛÓÚÇóÄ¿±êº¯Êýw?xyzÔÚÔ¼ÊøÌõ¼þx?y?z?aϵÄ×î´óÖµ
Áîgx?0,gy?0µÃפµãx?»¯ÎªÎÞÌõ¼þ¼«Öµ
g(x,y)?xy(a?x?y)?axy?x2y?xy2£¬x?0,y?0,x?y?a
Ôò gx?ay?2xy?y2£¬gy?ax?2xy?x£¬ ¡¡¡4·Ö
2aa,y?£® ¡¡¡6·Ö 33aaaÓÉʵ¼ÊÎÊÌâµÄÒâÒåÖª£¬x?,y?ʱ£¬g(x,y)È¡×îСֵ£¬´Ëʱz?£®
333a¼´Èý¸öÕýÊý·Ö±ðΪx?y?z?ʱ£¬ËüÃǵĵ¹ÊýÖ®»ý×îС£® ¡¡¡7·Ö
3Áîgx?0,gy?0µÃפµãx?·½·¨Èý Ìõ¼þ¼«Öµ£¬À¸ñÀÊÈÕº¯Êý
L(x,y,z)?1??(x?y?z?a)£¬x?0,y?0,z?0£¬ Ôò xyz1?L?????0,(1)?xx2yz?1?L?????0,(2)?yxy2z ? ¡¡¡4·Ö
?1?Lz?????0,(3)2xyz??x?y?z?a,(4)?ÓÉ(1) , (2), (3) ÁªÁ¢¿ÉµÃ x?y?z
a´úÈ루4£©µÃפµãx?y?z?£® ¡¡¡6·Ö
3ÓÉʵ¼ÊÎÊÌâµÄÒâÒåÖª£¬x?aaa,y?ʱ£¬g(x,y)È¡×îСֵ£¬´Ëʱz?£® 333a¼´Èý¸öÕýÊý·Ö±ðΪx?y?z?ʱ£¬ËüÃǵĵ¹ÊýÖ®»ý×îС£® ¡¡¡7·Ö
3£¨2£©Åжϼ¶Êý
nµÄÁ²É¢ÐÔ£¬ÈôÊÕÁ²£¬Çó¼¶ÊýµÄºÍ£® ?n3n?1?½â ÀûÓñÈÖµÅбð·¨
?3n?1?nn
nun?1n?131 lim ¡¡¡4·Ö ?lim???£¬ËùÒÔ¼¶ÊýÊÕÁ²£®1n??un??3n?1n3nan?1nn?1n?13n1¹¹ÔìÃݼ¶Êý?nx£¬ÏÈÇóÃݼ¶ÊýµÄÊÕÁ²°ë¾¶ ??lim||?limn?1??£¬
n??n??3ann3n?13?ËùÒÔÊÕÁ²°ë¾¶ÎªR?3£¬¹ÊÔÚ(?3,3)ÄÚÃݼ¶Êý¾ø¶ÔÊÕÁ²£®
?nnn?1ÁîÆäºÍº¯ÊýS(x)??nx£¨|x|?3£©£¬¹Ê S(1)??n£®
n?13n?13?x??nxn?11x3£¬ S(x)?[?n?xdx]'?[?nxn]'?[3]'?[]'?20x3?x(3?x)n?13n?131?3¹Ê S(1)?
n3?£® ¡¡¡7·Ö ?n34n?1?Ö£ÖÝÇṤҵѧԺ
2012-2013ѧÄêµÚ¶þѧÆÚÆÚÄ©¿¼ÊÔ ¸ßµÈÊýѧIB ÊÔ¾íA
ÊÔ¾íºÅ£ºA20130621
±¾ÌâµÃ·Ö
Ò»¡¢µ¥ÏîÑ¡ÔñÌâ(ÿÌâ3·Ö£¬¹²15·Ö)
1£®º¯Êýy?3e2xÊÇ·½³Ìy???4y?0µÄ £¨ B £©
£¨A£©Í¨½â£»£¨B£©Ìؽ⣻£¨C£©½â£¬µ«¼È·Çͨ½âÒ²·ÇÌؽ⣻£¨D£©ÒÔÉ϶¼²»¶Ô£®
d12lntdt=£¨ D £© 2£®
dx?x£¨A£©2lnx£» £¨B£©lnt£» £¨C£© lnx£» £¨D£©?lnx£® 3£®ÒÑÖª
222?f>0£¬Ôò£¨ A £© ?x£¨A£©f(x,y)¹ØÓÚxΪµ¥µ÷µÝÔö£» £¨B£©f(x,y)?0£»
?2f£¨C£©2>0£»
?x £¨D£©f(x,y)?x(y2?1)£®
£´£®Éèf(x,y)ÊÇÁ¬Ðøº¯Êý£¬Ôò£¨£Á£©
?40dx?2x0f(x,y)dy?£¨ B £©
44y2??40dy?1f(x,y)dx £» £¨£Â£©?dy?1401f(x,y)dx£»
4£¨£Ã£©
40dy?12y4?yf(x,y)dx £» £¨£Ä£©?dy?140yy2f(x,y)dx£®
45£®ÏÂÁм¶ÊýÖз¢É¢µÄÊÇ£¨ C £©
?1n1£¨£Á£©?(?1) £» £¨£Â£©?(?1)£» 2n(n?1)nn?1n?1n?nn?11 (£Ã£©?(?1)£» £¨£Ä£©?(?1)£® n?1nn?1n?1n??¶þ¡¢Ìî¿ÕÌâ(ÿÌâ3·Ö£¬¹²15·Ö) 1£®Ãݼ¶Êý
?axnn?0?nÔÚx??3ʱÌõ¼þÊÕÁ²£¬Ôò
?axnn?0?nµÄÊÕÁ²°ë¾¶R? __3____ £®