七年级下册数学题 大家帮忙解答，谢谢 七年级数学下册 133页,第八题，，，求答案，，谢谢，，怪急
\u4e03\u5e74\u7ea7\u6570\u5b66\u4e0b\u518c\u6839\u53f7\u989850\u9053\uff0c\u542b\u7b54\u6848\uff01\u8c22\u8c22\uff01\u6839\u53f71*\u6839\u53f72=1.4142135623731
\u6839\u53f72*\u6839\u53f73=2.44948974278318
\u6839\u53f73*\u6839\u53f74=3.46410161513775
\u6839\u53f74*\u6839\u53f75=4.47213595499958
\u6839\u53f75*\u6839\u53f76=5.47722557505166
\u6839\u53f76*\u6839\u53f77=6.48074069840786
\u6839\u53f77*\u6839\u53f78=7.48331477354788
\u6839\u53f78*\u6839\u53f79=8.48528137423857
\u6839\u53f79*\u6839\u53f710=9.48683298050514
\u6839\u53f710*\u6839\u53f711=10.4880884817015
\u6839\u53f711*\u6839\u53f712=11.4891252930761
\u6839\u53f712*\u6839\u53f713=12.4899959967968
\u6839\u53f713*\u6839\u53f714=13.490737563232
\u6839\u53f714*\u6839\u53f715=14.4913767461894
\u6839\u53f715*\u6839\u53f716=15.4919333848297
\u6839\u53f716*\u6839\u53f717=16.4924225024706
\u6839\u53f717*\u6839\u53f718=17.4928556845359
\u6839\u53f718*\u6839\u53f719=18.4932420089069
\u6839\u53f719*\u6839\u53f720=19.4935886896179
\u6839\u53f720*\u6839\u53f721=20.4939015319192
\u6839\u53f721*\u6839\u53f722=21.4941852602047
\u6839\u53f722*\u6839\u53f723=22.494443758404
\u6839\u53f723*\u6839\u53f724=23.4946802489415
\u6839\u53f724*\u6839\u53f725=24.4948974278318
\u6839\u53f725*\u6839\u53f726=25.4950975679639
\u6839\u53f726*\u6839\u53f727=26.4952825989835
\u6839\u53f727*\u6839\u53f728=27.495454169735
\u6839\u53f728*\u6839\u53f729=28.49561369755
\u6839\u53f729*\u6839\u53f730=29.4957624075053
\u6839\u53f730*\u6839\u53f731=30.4959013639538
\u6839\u53f731*\u6839\u53f732=31.4960314960472
\u6839\u53f732*\u6839\u53f733=32.4961536185438
\u6839\u53f733*\u6839\u53f734=33.4962684488885
\u6839\u53f734*\u6839\u53f735=34.4963766213207
\u6839\u53f735*\u6839\u53f736=35.4964786985977
\u6839\u53f736*\u6839\u53f737=36.4965751817893
\u6839\u53f737*\u6839\u53f738=37.4966665185053
\u6839\u53f738*\u6839\u53f739=38.4967531098403
\u6839\u53f739*\u6839\u53f740=39.496835316263
\u6839\u53f740*\u6839\u53f741=40.4969134626332
\u6839\u53f741*\u6839\u53f742=41.4969878424929
\u6839\u53f742*\u6839\u53f743=42.4970587217516
\u6839\u53f743*\u6839\u53f744=43.4971263418631
\u6839\u53f744*\u6839\u53f745=44.497190922574
\u6839\u53f745*\u6839\u53f746=45.4972526643093
\u6839\u53f746*\u6839\u53f747=46.4973117502507
\u6839\u53f747*\u6839\u53f748=47.4973683481517
\u6839\u53f748*\u6839\u53f749=48.4974226119286
\u6839\u53f749*\u6839\u53f750=49.4974746830583
\u6839\u53f750*\u6839\u53f751=50.4975246918104
\u6839\u53f751*\u6839\u53f752=51.4975727583349
\u6839\u53f752*\u6839\u53f753=52.4976189936267
\u6839\u53f753*\u6839\u53f754=53.497663500381
\u6839\u53f754*\u6839\u53f755=54.4977063737549
\u6839\u53f755*\u6839\u53f756=55.4977477020464
\u6839\u53f756*\u6839\u53f757=56.4977875673021
\u6839\u53f757*\u6839\u53f758=57.4978260458602
\u6839\u53f758*\u6839\u53f759=58.4978632088387
\u6839\u53f759*\u6839\u53f760=59.4978991225741
\u6839\u53f760*\u6839\u53f761=60.4979338490167
\u6839\u53f761*\u6839\u53f762=61.4979674460872
\u6839\u53f762*\u6839\u53f763=62.497999967999
\u6839\u53f763*\u6839\u53f764=63.4980314655502
\u6839\u53f764*\u6839\u53f765=64.4980619863884
\u6839\u53f765*\u6839\u53f766=65.4980915752513
\u6839\u53f766*\u6839\u53f767=66.4981202741852
\u6839\u53f767*\u6839\u53f768=67.4981481227448
\u6839\u53f768*\u6839\u53f769=68.4981751581748
\u6839\u53f769*\u6839\u53f770=69.4982014155762
\u6839\u53f770*\u6839\u53f771=70.4982269280583
\u6839\u53f771*\u6839\u53f772=71.4982517268779
\u6839\u53f772*\u6839\u53f773=72.4982758415674
\u6839\u53f773*\u6839\u53f774=73.4982993000518
\u6839\u53f774*\u6839\u53f775=74.4983221287567
\u6839\u53f775*\u6839\u53f776=75.4983443527075
\u6839\u53f776*\u6839\u53f777=76.4983659956211
\u6839\u53f777*\u6839\u53f778=77.4983870799903
\u6839\u53f778*\u6839\u53f779=78.4984076271615
\u6839\u53f779*\u6839\u53f780=79.4984276574072
\u6839\u53f780*\u6839\u53f781=80.4984471899924
\u6839\u53f781*\u6839\u53f782=81.4984662432367
\u6839\u53f782*\u6839\u53f783=82.4984848345714
\u6839\u53f783*\u6839\u53f784=83.4985029805924
\u6839\u53f784*\u6839\u53f785=84.4985206971104
\u6839\u53f785*\u6839\u53f786=85.4985379991962
\u6839\u53f786*\u6839\u53f787=86.4985549012236
\u6839\u53f787*\u6839\u53f788=87.4985714169094
\u6839\u53f788*\u6839\u53f789=88.4985875593503
\u6839\u53f789*\u6839\u53f790=89.4986033410578
\u6839\u53f790*\u6839\u53f791=90.4986187739901
\u6839\u53f791*\u6839\u53f792=91.498633869583
\u6839\u53f792*\u6839\u53f793=92.4986486387774
\u6839\u53f793*\u6839\u53f794=93.4986630920464
\u6839\u53f794*\u6839\u53f795=94.4986772394196
\u6839\u53f795*\u6839\u53f796=95.4986910905066
\u6839\u53f796*\u6839\u53f797=96.4987046545185
\u6839\u53f797*\u6839\u53f798=97.4987179402888
\u6839\u53f798*\u6839\u53f799=98.498730956292
\u6839\u53f799*\u6839\u53f7100=99.498743710662
\u6839\u53f7100*\u6839\u53f7101=100.498756211209
\u6839\u53f7101*\u6839\u53f7102=101.498768465435
\u6839\u53f7102*\u6839\u53f7103=102.49878048055
\u6839\u53f7103*\u6839\u53f7104=103.498792263485
\u6839\u53f7104*\u6839\u53f7105=104.498803820905
\u6839\u53f7105*\u6839\u53f7106=105.498815159223
\u6839\u53f7106*\u6839\u53f7107=106.498826284612
\u6839\u53f7107*\u6839\u53f7108=107.498837203014
\u6839\u53f7108*\u6839\u53f7109=108.498847920151
\u6839\u53f7109*\u6839\u53f7110=109.498858441538
\u6839\u53f7110*\u6839\u53f7111=110.49886877249
\u6839\u53f7111*\u6839\u53f7112=111.498878918131
\u6839\u53f7112*\u6839\u53f7113=112.498888883402
\u6839\u53f7113*\u6839\u53f7114=113.498898673071
\u6839\u53f7114*\u6839\u53f7115=114.498908291739
\u6839\u53f7115*\u6839\u53f7116=115.498917743847
\u6839\u53f7116*\u6839\u53f7117=116.498927033686
\u6839\u53f7117*\u6839\u53f7118=117.498936165397
\u6839\u53f7118*\u6839\u53f7119=118.498945142984
\u6839\u53f7119*\u6839\u53f7120=119.498953970317
\u6839\u53f7120*\u6839\u53f7121=120.498962651137
\u6839\u53f7121*\u6839\u53f7122=121.49897118906
\u6839\u53f7122*\u6839\u53f7123=122.498979587587
\u6839\u53f7123*\u6839\u53f7124=123.498987850103
\u6839\u53f7124*\u6839\u53f7125=124.498995979887
\u6839\u53f7125*\u6839\u53f7126=125.499003980111
\u6839\u53f7126*\u6839\u53f7127=126.499011853848
\u6839\u53f7127*\u6839\u53f7128=127.499019604074
\u6839\u53f7128*\u6839\u53f7129=128.499027233672
\u6839\u53f7129*\u6839\u53f7130=129.499034745437
\u6839\u53f7130*\u6839\u53f7131=130.499042142079
\u6839\u53f7131*\u6839\u53f7132=131.499049426222
\u6839\u53f7132*\u6839\u53f7133=132.499056600415
\u6839\u53f7133*\u6839\u53f7134=133.499063667128
\u6839\u53f7134*\u6839\u53f7135=134.499070628759
\u6839\u53f7135*\u6839\u53f7136=135.499077487635
\u6839\u53f7136*\u6839\u53f7137=136.499084246012
\u6839\u53f7137*\u6839\u53f7138=137.499090906086
\u6839\u53f7138*\u6839\u53f7139=138.499097469984
\u6839\u53f7139*\u6839\u53f7140=139.499103939774
\u6839\u53f7140*\u6839\u53f7141=140.499110317468
\u6839\u53f7141*\u6839\u53f7142=141.499116605016
\u6839\u53f7142*\u6839\u53f7143=142.499122804318
\u6839\u53f7143*\u6839\u53f7144=143.499128917217
\u6839\u53f7144*\u6839\u53f7145=144.499134945508
\u6839\u53f7145*\u6839\u53f7146=145.499140890934
\u6839\u53f7146*\u6839\u53f7147=146.499146755194
\u6839\u53f7147*\u6839\u53f7148=147.499152539938
\u6839\u53f7148*\u6839\u53f7149=148.499158246773
\u6839\u53f7149*\u6839\u53f7150=149.499163877261
\u6839\u53f7150*\u6839\u53f7151=150.499169432924
\u6839\u53f7151*\u6839\u53f7152=151.499174915245
\u6839\u53f7152*\u6839\u53f7153=152.499180325666
\u6839\u53f7153*\u6839\u53f7154=153.499185665592
\u6839\u53f7154*\u6839\u53f7155=154.499190936393
\u6839\u53f7155*\u6839\u53f7156=155.499196139401
\u6839\u53f7156*\u6839\u53f7157=156.499201275917
\u6839\u53f7157*\u6839\u53f7158=157.499206347207
\u6839\u53f7158*\u6839\u53f7159=158.499211354505
\u6839\u53f7159*\u6839\u53f7160=159.499216299015
\u6839\u53f7160*\u6839\u53f7161=160.499221181911
\u6839\u53f7161*\u6839\u53f7162=161.499226004337
\u6839\u53f7162*\u6839\u53f7163=162.49923076741
\u6839\u53f7163*\u6839\u53f7164=163.499235472219
\u6839\u53f7164*\u6839\u53f7165=164.499240119825
\u6839\u53f7165*\u6839\u53f7166=165.499244711267
\u6839\u53f7166*\u6839\u53f7167=166.499249247557
\u6839\u53f7167*\u6839\u53f7168=167.499253729681
\u6839\u53f7168*\u6839\u53f7169=168.499258158604
\u6839\u53f7169*\u6839\u53f7170=169.499262535269
\u6839\u53f7170*\u6839\u53f7171=170.499266860594
\u6839\u53f7171*\u6839\u53f7172=171.499271135477
\u6839\u53f7172*\u6839\u53f7173=172.499275360797
\u6839\u53f7173*\u6839\u53f7174=173.499279537409
\u6839\u53f7174*\u6839\u53f7175=174.499283666151
\u6839\u53f7175*\u6839\u53f7176=175.499287747842
\u6839\u53f7176*\u6839\u53f7177=176.499291783282
\u6839\u53f7177*\u6839\u53f7178=177.499295773251
\u6839\u53f7178*\u6839\u53f7179=178.499299718514
\u6839\u53f7179*\u6839\u53f7180=179.499303619819
\u6839\u53f7180*\u6839\u53f7181=180.499307477896
\u6839\u53f7181*\u6839\u53f7182=181.499311293459
\u6839\u53f7182*\u6839\u53f7183=182.499315067208
\u6839\u53f7183*\u6839\u53f7184=183.499318799826
\u6839\u53f7184*\u6839\u53f7185=184.499322491981
\u6839\u53f7185*\u6839\u53f7186=185.499326144329
\u6839\u53f7186*\u6839\u53f7187=186.499329757509
\u6839\u53f7187*\u6839\u53f7188=187.499333332148
\u6839\u53f7188*\u6839\u53f7189=188.49933686886
\u6839\u53f7189*\u6839\u53f7190=189.499340368245
\u6839\u53f7190*\u6839\u53f7191=190.499343830891
\u6839\u53f7191*\u6839\u53f7192=191.499347257373
\u6839\u53f7192*\u6839\u53f7193=192.499350648255
\u6839\u53f7193*\u6839\u53f7194=193.49935400409
\u6839\u53f7194*\u6839\u53f7195=194.499357325416
\u6839\u53f7195*\u6839\u53f7196=195.499360612765
\u6839\u53f7196*\u6839\u53f7197=196.499363866655
\u6839\u53f7197*\u6839\u53f7198=197.499367087593
\u6839\u53f7198*\u6839\u53f7199=198.499370276079
\u6839\u53f7199*\u6839\u53f7200=199.4993734326
\u6839\u53f7200*\u6839\u53f7201=200.499376557634
\u8bbe\u8001\u5f20\u4e70\u4e86x\u53ea
x+2\u22642/3(2x-1)
3x+6\u22644x-2
-x\u2264-8
x\u22658
\u6240\u4ee5\uff0c\u4e00\u5e74\u524d\u8001\u5f20\u81f3\u5c11\u4e70\u4e868\u53ea\u3002
\u4e0d\u7406\u89e3\u53ef\u8ffd\u95ee\uff0c\u6709\u5e2e\u52a9\u8bf7\u91c7\u7eb3\uff0c\u8c22\u8c22\uff01
|3a+4b-c|+1/4（c-2b）²=0
则 3a+4b-c＝0
c-2b＝0
所以a：b：c=－2：3：6
2.由题意可设 甲乙两地之间的水路、公路路程分别为x,y km
则有 y-x=40 x/24=3+ y/40
所以 x=240 y=280
甲乙两地之间的水路路程为240 km
甲乙两地之间的公路路程为280 km
轮船行驶的时间为x/24=10 h
汽车行驶的时间为y/40=7 h
3. x+2y+3z=10, 4x+3y+2z=15两式相加得 5x+5y+5z=25
所以 5（x+y+z）=25=> x+y+z=5
4. 5x=10+5y; 4x=(2+4)y
5.由题意可设用x张做盒身,y张做盒底才能配套
则 2*16x=43y x+y=150
所以 x=86 y=64所以用86张做盒身,64张做盒底才能配套
希望满意！！！望采纳！！！如果觉得好，望赞同！！！
1.|3a+4b-c|+1/4（c-2b）²=0则：3a+4b-c=0; c-2b=0;
所以：c=2b; 3a+4b-2b=0; 3a=-2b; a=-(2/3)b; c=2b;
所以：a:b:c=(-2/3):1:2=-2:3:6;
2.设轮船的行驶时间为x (h);则汽车的行驶时间为（x-3) h;
甲乙之间的水路长：24x(km); 公路长：(24x+40) km;
按照汽车的行驶：24x+40=40(x-3); 16x=160; x=10;
所以甲乙之间的水路长=24x=240km; 公路长=280km;
汽车的行驶时间为=x-3=7 h; 轮船的行驶时间=10 h;
3.把两式x+2y+3z=10,4x+3y+2z=15相加得：5x+5y+5z=25;
所以：x+y+z=5
4.设甲，乙速度分别为x米/秒，y米/秒．
由题意可得：5x-5y=10； 4x-4y=2y；
所以得x=6 ； y=4
5.设用x张做盒身，用（150-x）张做盒底：
则32x＝43×（150-x）
x＝86（张做盒身）
150-86＝64（张做盒底）
答：用86张做盒身，64张做盒底。
(1)
a：b：c=2:3:6
(2)设水路为X，则公路为40+X
X/24=（40+X）/40 +3 时间相等
得X=240
水路240km 公路280km 水路时间10小时，公路时间7小时
（3）x+2y+3z=10, A
4x+3y+2z=15 B
AB 左右相加
5（x+y+z）=25
x+y+z=5
（4）
5y+10=5x A
6y=4x B
得X=6 Y=4
(5)
设做盒身X 张，做盒底Y张
X+Y=150 A
16X=43Y/2 B
得X= 86 Y=64
第一题：利用求：3a+4b+c=0, c-2b=0 求出a=-2/3b,c=2b,所以答案是：-2/3:1:2
第二题：设汽车行驶了x个小时，则轮船行驶了：x+3个小时可以列：40x=24(x+3)+40,求得：x=7那么答案是：汽车行驶了7个小时，走了280km,船走了10h,240km.
第三题：把两式相加，得5x+5y+5z=25,所以x+y+z=5
第四题：5x=5y+10 4x=6y
第五题：设用x个做盒身，用150-x个做盒底，则可列：2*16x=43(150-x),解得x=86,
1.|3a＋4b－c|＋1/4(c－2b)²=0，考虑到绝对值和平方都是非负的，则有：3a＋4b－c=0且c－2b=0，解得b=(1/2)c，代入第一个中，得：a=－(1/3)c，则a：b：c=(－1/3)：(1/2)：1=(－2)：3：6。2.假设水路长xkm，则公路长(x+40)km,设轮船花了y小时到达乙地，则汽车花了(y-3)小时
24y=x
40(y-3)=x+40
解方程组，得：
x=240
y=103.x+2y+3z=10,4x+3y+2z=15
两式相加，得
x+2y+3z+4x+3y+2z=10+15
5x+5y+5z=25
5(x+y+z)=25
x+y+z=54.解：设甲，乙速度分别为x米/秒，y米/秒．
由题意可得：{5x-5y=10⑴ 4x-4y=2y⑵
把1式变形x=5y+10/5
把x=5y+10/5代入2式中
得，4x(5y+10/5)-4y=2y
∴y=4
把y=4代入1式中
得，5x-5x4=10
∴x=6
∴方程组的解为{x=6 y=45.设用n张做盒身，用（4-n）张做盒底，列方程式如下：
16n×2＝43×（4-n）
32n＝172-43n
75n＝172
n＝2.29（张做盒身）
4-n＝4-2.3＝1.71（张做盒底）
答：用2.29张做盒身，1.71张做盒底。
这只是理论计算，实际上因为出现小数，必定会出现零角料，
1: 绝对值和平方均>=0 故绝对值和平方只能等于0 故c=2b 3a=-2b（你加减号写错了吧）
2:设x为汽车行驶时间。根据路程列方程 20x+40=24(x+3) 将x解出即可求出所有问题
3:将两方程等式左右分别相加得5x+5y+5z=25 x+y+z=5
4:根据路程的关系分别所列方程为 5x=5y+10 4x=(2+4)y
5:根据题目要求关系列出方程组即可，设盒身x个，盒底y个，则一个罐头盒有一盒身两盒底 x=2y 共有150块铁皮 x/16+y/43=150
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