习题与自测题详解
习题1.1
1.(1)不是,对应法则不同. 也可用值域不同断定. (2)是,定义域相同,对应法则等价. (3)不是,定义域不同. (4)不是,定义域不同. 2.(1)9?x2?0,??3?x?3. (2)
x2?3x?2?0,?x?1且x?2.
(3)
??1?x?0,?2?x?0.??2?x?1. (4)[?1,0)[0,2)?[?1,2).
13.(1)f(1)?0,f(?11?(?12)1?a1?12)??3,f(1)??a?a?1?1. 1?(?12)a1?1a1?1aa(2)f(?3)?2?3?108,f(0)?2?1,f(3)?3?1?2.
4.
(1)y?x3?7,?x?3y?7,?反函数为y?3x?7;
(2)y?log3y?1,?反函数为y?3x3(x?1),?x??1.5.
q?[0,800],R(q)?150q; q?(800,1 600],R(q)?150?800?150?0.8(800?x)?120x?24 000.?R(q)???150q, q?[0,800],?120q?24 000,q?(800,1 600].6.略.
习题 1.2
1.
1
(1)(??,?1),(?1,??);(2)(??,??);(3)(0,??);(4)(2k???,2k???],(2k???,2k??3?]( 2222k?Z);(5)(2k???,2k?],(2k?,2k???](k?Z);
(6)(2k???,2k??2?2)(k?Z).2.
(1)f(?x)?[(?x)2?1]|?x|?(x2?1)|x|?f(x),?是偶函数; x)?e?x(2)f(??exex?e?x2??2??f(x), ?是奇函数;(3)f(x)定义域不对称于原点; 故为非奇非偶函数;
(4)1?x1?x?0,?(1?x)(1?x)?0,(x?1)(1?x)?0,?x?(?1,1). f(?x)?ln1?x1?x1?x??ln1?x??f(x), ?是奇函数.3.
?x2?, x?[0,2) f(x)???(x?2)2,x?[2,4)或f(x)?(x?2k)2,x?[2k,2k?2)(k?0,1,2,3)?(x?4)2,x?[4,6)??(x?6)2,x?6 习题1.3
1.
(1)y?2x?1; (2)y?arccos(3x?4);(3)y?tanx?1; (4)y?1 ln(x?1).2.
(1)y?u3,u?2x?1; (2)y?2u,u?v3,v?sinx;(3)y?lgu,u?cosv,v?x2
?1; (4)y?u,u?lnv,v?lnw,w?x.习题 1.4
1. 设Q?a?bp,则??1 500?a?50b,;?a?3 000,?1 200?a?60b.??b?30. ,故Q?3 000?30p. 2.
2
C(q)?2 000+15q,R(q)?20q,
L(q)?R(q)?C(q)?5q?2 000?0,?q?400.答:该厂每天至少应生产400套.
3. C(q)?700+500q,R(q)?900q,L(q)?R(q)?C(q)?400q?700.
4. y?4?200x800x800x?1??2??40;?,?x?40. x2x2x2答:全年经济购存费4万元,经济批量40件.
自测题1
1. (1)3,-4;(2)(??,0)(3)y?x?x2?1(x?R); (0,??),??1,1?;
(4)f(?x)??f(x),x?(?2,2); (5)y?eu,u?tanv,v?1/x. 2. (1)?; (2)?; (3)?; (4)?; (5)?. 3. (1)B; (2)A; (3)A; (4)C; (5)D.
?16?x2?0,?x?4,4. (1)????x?(0,1)(1,4]; ?1?x?0.?lnx?0. (2)sinx?0?x?(2k?,2k???)(k?Z).5. (1)f(?x)?e?x?ex??(ex?e?x)??f(x),?是奇函数; (2)f(?x)?lnsin(?x)?ln(?sinx)?f(x),?是偶函数.6.
22
13vv??r2h, ?r?(h?0).
3?h
习题 2.1
1.分别求出数列的前几项,标在数轴上,观察可得: (1)1,(2)0,(3)1,(4)0,(5)0,(6)无.
2. 极限均为8,由此可得常数的极限为该常数;所列五个函数的极限如下表,由表中的结论可联想到逐个考察另五类基本初等函数在六种极限过程之下,极限是否存在、存在时极限是什么?这是一件有意义的工作:
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