34.2 ʽӦ
1xyֱʾεijͿlʾεܳSʾεl2(xy)Sxy
2УSΪֵxy2xy֪ܳСֵΪ4S 3ڵ1УܳlΪֵxy
xy2
2
֪SֵΪ
16
2
2
l2
?ab?
4ʽab2ab(abR)ıab2abab???2?
5õļʽУ
ab2ab2abܡ ba112ab
? һѡ
1x4yxAֵ6 BСֵ6 Cֵ2 DûСֵ yx45ʱȡСֵ6.
1
42x4
a2b2
2
(abR),
1
(B) x4
x4
1146.ҽx4ʱxx4x4
2abΪʵab322СֵΪ(B) A6 B42 C22 D8 2222
ababab2242.
3
3֪xyxy4A1 B2 C22 D.2
yxȡСֵʱxֵ(B) xy
yx2xyxy2422ʱ
4
yxxy2. xy4СӼصҵʱٷֱΪab(ab)ȫ̵ƽʱΪv(A) Aavab Bvab C.abvDv
ab2
ab2
2abab2ab2ababab?
ssab2ab2b
2sصҵؾΪsv
aba
2abab. ab1ab5ab1Plg alg bQ(lg alg b)Rlg (B)
22ARPQ BPQR CQPR DPRQ
ab1lg a0lg b0. ɻʽPQQlg ablg
11xy6֪x0y0lg 2lg 8lg 2Сֵ________
x3yx0y0lg 2lg 8lg 22
xyx3yab2
RPQR.
11x3y2x3y1࣫
x3yxx3y3yx2223yx3y𰸣4
3yx4ҽx3yʱȡȺţ x3y7֪x0y03x4y52xyֵΪ________ 11?3x4y?212525
2xy3x4y??.
66?2?642425
𰸣 24
1??8ʽyx(13x)?0x?ֵ________ 3??
111?3x13x?21
0x13x0.x(13x)(3x)(13x)??3
2333??11
. 412
1
𰸣
12
5x4x5
9֪xݣf(x)Сֵ
2x2
5x4x5x211
xݣx20.f(x)(x2)2.
2x2x2x2x2
1
x3ʱȺųʵx3ʱf(x)min2. x2
2
2
2
10P(12)ֱlxᡢyֱAB㣬ABOСʱֱlķ̣
A(a0)B(0b)a0b0lķΪ1֡lP㣬121࣫1εSab. ab2
12
ɣ1?abb2a22ab?ab8ҽb2aa2b4ʱSmin4.
xyabablķΪ12xy40.
24? һѡ
11֪a(x12)b(4y)ab93СֵΪ(C) A23 B12 C6 D32
abab04(x1)2y02xy29329323
2xyxyxyxyxy6.ҽ2xy1ʱȡȺţСֵΪ6.
12֪MǶֵиУabûֵ(D) AabM
BabRabM Ca0b0abM Dab0abM
2
2
?ab?ababκʵababʱȺų
ab??2?2?
֪ABCֵDвڵȺųDûֵ
2
22
?1a?13֪ʽ(xy)??9ʵxyʵaСֵΪ
xy?
?
(B)
A2 B4 C6 D8
axy?1a?22
(xy)??1a12aa(1a).(1a)9a?xy?
yx4.
14xyΪʵ4xyxy12xyֵ________
33?2xy?2222
4xyxy1(2xy)13xy(2xy)12xy1??22?2?2
82102102
(2xy)ܣ2xy.
555210
𰸣
5
15a0b0a1a1bֵΪ________
2a12ab2
2
222a1b32
a1b2a1b2ܡ.
2224
2
2
2
2
2
2
2
b2
2
b2
22
12322
ҽ2a1b?baʱȡȺţ
2432
𰸣
4
1?x1x2?ĴС
16֪f(x)lg x(xR)x1x2Rж[f(x1)f(x2)]f??2?2?֤
1?x1x2?.֤ [f(x1)f(x2)]f??2?2?f(x1)f(x2)lg x1lg x2lg(x1x2)