二元一次方程难题
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1.2x+9y=81
3x+y=34
2.9x+4y=35
8x+3y=30
3.7x+2y=52
7x+4y=62
4.4x+6y=54
9x+2y=87
5.2x+y=7
2x+5y=19
6.x+2y=21
3x+5y=56
7.5x+7y=52
5x+2y=22
8.5x+5y=65
7x+7y=203
9.8x+4y=56
x+4y=21
10.5x+7y=41
5x+8y=44
11.7x+5y=54
3x+4y=38
12.x+8y=15
4x+y=29
13.3x+6y=24
9x+5y=46
14.9x+2y=62
4x+3y=36
15.9x+4y=46
7x+4y=42
16.9x+7y=135
4x+y=41
17.3x+8y=51
x+6y=27
18.9x+3y=99
4x+7y=95
19.9x+2y=38
3x+6y=18
20.5x+5y=45
7x+9y=69
21.8x+2y=28
7x+8y=62
22.x+6y=14
3x+3y=27
23.7x+4y=67
2x+8y=26
24.5x+4y=52
7x+6y=74
25.7x+y=9
4x+6y=16
26.6x+6y=48
6x+3y=42
27.8x+2y=16
7x+y=11
28.4x+9y=77
8x+6y=94
29.6x+8y=68
7x+6y=66
30.2x+2y=22
7x+2y=47
1) 66x+17y=3967
25x+y=1200
\u7b54\u6848\uff1ax=48 y=47
(2) 18x+23y=2303
74x-y=1998
\u7b54\u6848\uff1ax=27 y=79
(3) 44x+90y=7796
44x+y=3476
\u7b54\u6848\uff1ax=79 y=48
(4) 76x-66y=4082
30x-y=2940
\u7b54\u6848\uff1ax=98 y=51
(5) 67x+54y=8546
71x-y=5680
\u7b54\u6848\uff1ax=80 y=59
(6) 42x-95y=-1410
21x-y=1575
\u7b54\u6848\uff1ax=75 y=48
(7) 47x-40y=853
34x-y=2006
\u7b54\u6848\uff1ax=59 y=48
(8) 19x-32y=-1786
75x+y=4950
\u7b54\u6848\uff1ax=66 y=95
(9) 97x+24y=7202
58x-y=2900
\u7b54\u6848\uff1ax=50 y=98
(10) 42x+85y=6362
63x-y=1638
\u7b54\u6848\uff1ax=26 y=62
(11) 85x-92y=-2518
27x-y=486
\u7b54\u6848\uff1ax=18 y=44
(12) 79x+40y=2419
56x-y=1176
\u7b54\u6848\uff1ax=21 y=19
(13) 80x-87y=2156
22x-y=880
\u7b54\u6848\uff1ax=40 y=12
(14) 32x+62y=5134
57x+y=2850
\u7b54\u6848\uff1ax=50 y=57
(15) 83x-49y=82
59x+y=2183
\u7b54\u6848\uff1ax=37 y=61
(16) 91x+70y=5845
95x-y=4275
\u7b54\u6848\uff1ax=45 y=25
(17) 29x+44y=5281
88x-y=3608
\u7b54\u6848\uff1ax=41 y=93
(18) 25x-95y=-4355
40x-y=2000
\u7b54\u6848\uff1ax=50 y=59
(19) 54x+68y=3284
78x+y=1404
\u7b54\u6848\uff1ax=18 y=34
(20) 70x+13y=3520
52x+y=2132
\u7b54\u6848\uff1ax=41 y=50
(21) 48x-54y=-3186
24x+y=1080
\u7b54\u6848\uff1ax=45 y=99
(22) 36x+77y=7619
47x-y=799
\u7b54\u6848\uff1ax=17 y=91
(23) 13x-42y=-2717
31x-y=1333
\u7b54\u6848\uff1ax=43 y=78
(24) 28x+28y=3332
52x-y=4628
\u7b54\u6848\uff1ax=89 y=30
(25) 62x-98y=-2564
46x-y=2024
\u7b54\u6848\uff1ax=44 y=54
(26) 79x-76y=-4388
26x-y=832
\u7b54\u6848\uff1ax=32 y=91
(27) 63x-40y=-821
42x-y=546
\u7b54\u6848\uff1ax=13 y=41
(28) 69x-96y=-1209
42x+y=3822
\u7b54\u6848\uff1ax=91 y=78
(29) 85x+67y=7338
11x+y=308
\u7b54\u6848\uff1ax=28 y=74
(30) 78x+74y=12928
14x+y=1218
\u7b54\u6848\uff1ax=87 y=83
(31) 39x+42y=5331
59x-y=5841
\u7b54\u6848\uff1ax=99 y=35
(32) 29x+18y=1916
58x+y=2320
\u7b54\u6848\uff1ax=40 y=42
(33) 40x+31y=6043
45x-y=3555
\u7b54\u6848\uff1ax=79 y=93
(34) 47x+50y=8598
45x+y=3780
\u7b54\u6848\uff1ax=84 y=93
(35) 45x-30y=-1455
29x-y=725
\u7b54\u6848\uff1ax=25 y=86
(36) 11x-43y=-1361
47x+y=799
\u7b54\u6848\uff1ax=17 y=36
(37) 33x+59y=3254
94x+y=1034
\u7b54\u6848\uff1ax=11 y=49
(38) 89x-74y=-2735
68x+y=1020
\u7b54\u6848\uff1ax=15 y=55
(39) 94x+71y=7517
78x+y=3822
\u7b54\u6848\uff1ax=49 y=41
(40) 28x-62y=-4934
46x+y=552
\u7b54\u6848\uff1ax=12 y=85
(41) 75x+43y=8472
17x-y=1394
\u7b54\u6848\uff1ax=82 y=54
(42) 41x-38y=-1180
29x+y=1450
\u7b54\u6848\uff1ax=50 y=85
(43) 22x-59y=824
63x+y=4725
\u7b54\u6848\uff1ax=75 y=14
(44) 95x-56y=-401
90x+y=1530
\u7b54\u6848\uff1ax=17 y=36
(45) 93x-52y=-852
29x+y=464
\u7b54\u6848\uff1ax=16 y=45
(46) 93x+12y=8823
54x+y=4914
\u7b54\u6848\uff1ax=91 y=30
(47) 21x-63y=84
20x+y=1880
\u7b54\u6848\uff1ax=94 y=30
(48) 48x+93y=9756
38x-y=950
\u7b54\u6848\uff1ax=25 y=92
(49) 99x-67y=4011
75x-y=5475
\u7b54\u6848\uff1ax=73 y=48
(50) 83x+64y=9291
90x-y=3690
\u7b54\u6848\uff1ax=41 y=92
(51) 17x+62y=3216
75x-y=7350
\u7b54\u6848\uff1ax=98 y=25
(52) 77x+67y=2739
14x-y=364
\u7b54\u6848\uff1ax=26 y=11
(53) 20x-68y=-4596
14x-y=924
\u7b54\u6848\uff1ax=66 y=87
(54) 23x+87y=4110
83x-y=5727
\u7b54\u6848\uff1ax=69 y=29
(55) 22x-38y=804
86x+y=6708
\u7b54\u6848\uff1ax=78 y=24
(56) 20x-45y=-3520
56x+y=728
\u7b54\u6848\uff1ax=13 y=84
(57) 46x+37y=7085
61x-y=4636
\u7b54\u6848\uff1ax=76 y=97
(58) 17x+61y=4088
71x+y=5609
\u7b54\u6848\uff1ax=79 y=45
(59) 51x-61y=-1907
89x-y=2314
\u7b54\u6848\uff1ax=26 y=53
(60) 69x-98y=-2404
21x+y=1386
\u7b54\u6848\uff1ax=66 y=71
(61) 15x-41y=754
74x-y=6956
\u7b54\u6848\uff1ax=94 y=16
(62) 78x-55y=656
89x+y=5518
\u7b54\u6848\uff1ax=62 y=76
(63) 29x+21y=1633
31x-y=713
\u7b54\u6848\uff1ax=23 y=46
(64) 58x-28y=2724
35x+y=3080
\u7b54\u6848\uff1ax=88 y=85
(65) 28x-63y=-2254
88x-y=2024
\u7b54\u6848\uff1ax=23 y=46
(66) 43x+50y=7064
85x+y=8330
\u7b54\u6848\uff1ax=98 y=57
(67) 58x-77y=1170
38x-y=2280
\u7b54\u6848\uff1ax=60 y=30
(68) 92x+83y=11586
43x+y=3010
\u7b54\u6848\uff1ax=70 y=62
(69) 99x+82y=6055
52x-y=1716
\u7b54\u6848\uff1ax=33 y=34
(70) 15x+26y=1729
94x+y=8554
\u7b54\u6848\uff1ax=91 y=14
(71) 64x+32y=3552
56x-y=2296
\u7b54\u6848\uff1ax=41 y=29
(72) 94x+66y=10524
84x-y=7812
\u7b54\u6848\uff1ax=93 y=27
(73) 65x-79y=-5815
89x+y=2314
\u7b54\u6848\uff1ax=26 y=95
(74) 96x+54y=6216
63x-y=1953
\u7b54\u6848\uff1ax=31 y=60
(75) 60x-44y=-352
33x-y=1452
\u7b54\u6848\uff1ax=44 y=68
(76) 79x-45y=510
14x-y=840
\u7b54\u6848\uff1ax=60 y=94
(77) 29x-35y=-218
59x-y=4897
\u7b54\u6848\uff1ax=83 y=75
(78) 33x-24y=1905
30x+y=2670
\u7b54\u6848\uff1ax=89 y=43
(79) 61x+94y=11800
93x+y=5952
\u7b54\u6848\uff1ax=64 y=84
(80) 61x+90y=5001
48x+y=2448
\u7b54\u6848\uff1ax=51 y=21
(81) 93x-19y=2
86x-y=1548
\u7b54\u6848\uff1ax=18 y=88
(82) 19x-96y=-5910
30x-y=2340
\u7b54\u6848\uff1ax=78 y=77
(83) 80x+74y=8088
96x-y=8640
\u7b54\u6848\uff1ax=90 y=12
(84) 53x-94y=1946
45x+y=2610
\u7b54\u6848\uff1ax=58 y=12
(85) 93x+12y=9117
28x-y=2492
\u7b54\u6848\uff1ax=89 y=70
(86) 66x-71y=-1673
99x-y=7821
\u7b54\u6848\uff1ax=79 y=97
(87) 43x-52y=-1742
76x+y=1976
\u7b54\u6848\uff1ax=26 y=55
(88) 70x+35y=8295
40x+y=2920
\u7b54\u6848\uff1ax=73 y=91
(89) 43x+82y=4757
11x+y=231
\u7b54\u6848\uff1ax=21 y=47
(90) 12x-19y=236
95x-y=7885
\u7b54\u6848\uff1ax=83 y=40
(91) 51x+99y=8031
71x-y=2911
\u7b54\u6848\uff1ax=41 y=60
(92) 37x+74y=4403
69x-y=6003
\u7b54\u6848\uff1ax=87 y=16
(93) 46x+34y=4820
71x-y=5183
\u7b54\u6848\uff1ax=73 y=43
(94) 47x+98y=5861
55x-y=4565
\u7b54\u6848\uff1ax=83 y=20
(95) 30x-17y=239
28x+y=1064
\u7b54\u6848\uff1ax=38 y=53
(96) 55x-12y=4112
79x-y=7268
\u7b54\u6848\uff1ax=92 y=79
(97) 27x-24y=-450
67x-y=3886
\u7b54\u6848\uff1ax=58 y=84
(98) 97x+23y=8119
14x+y=966
\u7b54\u6848\uff1ax=69 y=62
(99) 84x+53y=11275
70x+y=6790
\u7b54\u6848\uff1ax=97 y=59
(100) 51x-97y=297
19x-y=1520
\u7b54\u6848\uff1ax=80 y=39
当x=5/2时取得最小值3/4.
x^ -5x+7=(x-5/2)^2+3/4>=3/4>0
x=5/2时,最小值为3/4
x^2 -5x+7=(x^2-2*5/2x+(5/2)^2)+3/4=(x-5/2)^2+3/4
因为：(x-5/2)^2>=0，所以(x-5/2)^2+3/4>0
当x=5/2时，(x-5/2)^2=0，该式最小，为3/4
因为b^2-4ac 小于0 且二次项大于0 所以代数式的值总是正数
x=-b/2a 时 代数式的值最小
0.75
学过初2的函数...应该就会了....
x^2 -5x+7=x^2 -5x+25/4+3/4=(x-5/2)^2+3/4>0当x取5/2时,这个代数式的值最小,最小值为3/4 。
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绛旓細(1)璁捐鍒掓媶闄骞虫柟绫筹紝鏂板缓y骞虫柟绫筹紝鍒鏂圭▼缁勫緱锛歺+y=7200锛110%x+80%y=x+y銆傝仈绔嬭В寰楋細x=4800锛寉=2400 鍗宠鍒掓媶闄4800骞虫柟绫筹紝鏂板缓2400骞虫柟绫炽(2)鍘熻鍒掕姳璐圭殑璧勯噾涓80*4800+700*2400=2064000锛堝厓锛夊疄闄呰姳璐圭殑璧勯噾涓80*110%*4800+700*80%*2400=1766400锛堝厓锛夎妭绾﹁祫閲戜负2064000-1766400=...
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