2021-2022学年河南省信阳市浉河区九年级（上）第三次月考数学试卷（附答案详解）

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2021-2022
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13%X]=1,x-4.2ᓽæḄ±2,=>Ḅî᪷4.ூ᪆௃Ú⚪ὃGH᪷Ḅᑨ|+ᐗ;<=>a/+bx+c=0(aõ0)Ḅ᪷xA=b2-4acᨵ᝞gᐵN(1)4>0o=>ᨵ¥'«LḄäᦪ᪷(2)4=0o=>ᨵ¥«LḄäᦪ᪷(3)4<00=>üᨵäᦪ᪷.ÇὃGHᐗ;<=>ḄḄ~ý.(1)⌕àá=>ᨵ¥'«LḄäᦪ᪷+ᓽàá4>0ᓽ6(2)ÿ=1Øᐭ=>(¿-3)(%-2)=|m|,ᚗḄḄ.18.ூᫀ௃:(1)23(2)77.5(3)ᵬᙠ!"#Ḅ᣸%&☠(ᳮᵫ᝞,-•.•/"#ᵬḄᡂ1ᜧ345ᦪ77.5ᑖᐸ%9ᙠ!:25%;(<"#=Ḅᡂ1>345ᦪ79.5ᑖᐸ%9ᙠ!:25%;@•••ᵬᙠ!"#Ḅ᣸%&☠((4)400xᱯF=224(H).•IJ/"#ᡂ1KLMᙳᦪ76.9ᑖḄHᦪP224H.ூ᪆௃ூᑖ᪆௃R⚪T⌕ὃW⚣ᦪᑖYZ[ஹ45ᦪ]᪵RIJ_`⚪Ḅᐵbc᪷eZ[⚪ᡠ◤ᦪe]45ᦪḄhijkiஹ᪵RIJ_`lmḄnᵨ.(1)᪷e⚣ᦪᑖYZ[Ḅᦪep(2)᪷e45ᦪḄhip(3)qᔜsᡂ1t!"#Ḅ45ᦪuvpᫀ(4)ᵨ_Hᦪwx᪵R4/"#ᡂ1KLMᙳᦪ76.9ᑖḄHᦪᡠᓰuzp.ூ௃-(1)ᙠ{9|}4/"#ᙠ80ᑖx~(80ᑖ)Ḅᨵ15+8=23(H)ᦑᫀP23(2)/"#50Hᡂ1Ḅ45ᦪc25ஹ26ᦪeḄMᙳᦪ25ஹ26ᦪeᑖP77ஹ78,ᦑᫀP77.5(3)ᫀ(4)ᫀ.

1419.ூᫀ௃-(1)&B1G᝞[ᡠ,4282c2᝞[ᡠ;(2)᝞[4P6,-1);ூ᪆௃(1)᪷e᪀AஹBஹC180஺@Ḅ&ஹஹ6Ḅ5ᯠ@9¡¢ᓽpM¤@Ḅ%ஹ%ஹḄ5ᯠ@9¡¢ᓽp(2)᪷eḄhiᔠ[§¡¢¨©ᓽP4.R⚪ὃWªᑭᵨ¬ᣚ®[ᑭᵨ¯°¬ᣚ®[±²³´᪀µ¶Ḅ5c⚪Ḅᐵb.20.ூᫀ௃-(1)·¸ᣵḄº§Ḅ»¼PXC77Lᑣ(40-2x)2=484,BP40-2x=±22,%=31(Âᔠ⚪kÃÄ)x=9,2•¸ᣵḄº§Ḅ»¼P9czn.(2)Ç☢Éᨵᨬᜧ.·¸ᣵḄ>º§Ḅ»¼Pacm,ËÌḄÇ☢ÉPysn2,ᑣytaḄÐᦪᐵÑP-y=4(40—2a)a,ᓽy=-8a2+160a,ᓽy=-8(a-10)2+800,:.a=10Ó,yᨬᜧ=800.ᓽ¸ᣵḄº§Ḅ»¼P10c஻7Ó¼§ËÌḄÇ☢ÉᨬᜧP800cm2.ூ᪆௃(1)Ꮇ·¸ᣵḄº§Ḅ»¼P×Ø᪷e⚪k(40-2x)2=484,ᓽp(2)Ꮇ·¸ᣵḄº§Ḅ»¼PÙÚËÌḄÇ☢ÉPycm2,ᑣytxḄÐᦪᐵÑP-y=4(40-2a)a,ᑭᵨÛ9Ðᦪᨬᓽp.R⚪T⌕ὃWªÛ9ÐᦪḄᵨᑮᐵbÝÞßà᪷eáâᐵѵ¶ḄᑡÐᦪᐵÑäcåæ⚪Ḅᐵb.21.ூᫀ௃-(1)ঝX]=0,ᡭ=-2;®-2

15õö÷ᔣ~⚔ᙶ᪗(L0),ᐵ3°¯ü=1°Ḅý(0,1),(2,1),ᵨþÿ
᝞2ᡠঝᦪᔠy=4——2x+1=4Ḅ%[=-1,=3ঞ!"ᑏ
$ᵫ2&'()*+2%+1<4Ḅ$,-1cx<3(3)ᓃ2+4.>0ᐵ1xḄ'()a/+bx+c>0(a>0)Ḅ$,X>f+J024acᡈx<-2ᔆ:2a2a᮱-4ac=0ᐵ1xḄ'()a/+bx+c>0(a>0)Ḅ$,ᑐ'+4/+4ac<0ᐵ1xḄ'()a/+bx+c>0(a>0)Ḅ$,ᐰ78ᦪ.ூ᪆௃(1)ঝ+2M+4ᑐ=0Ḅ>=0,%=-22ᦑ@ᫀ—0,%——2;2ঞ'()+2/+B20Ḅ$+24C40ᦑ@ᫀ+24xW0(2)D@ᫀ(3)D@ᫀ(1)EFGHᑭᵨKᦪ
'()-2/+4x20Ḅ$(2)✌ᐜ
y=/-2%+1ḄKᦪNᑭᵨy=4/-2O+1=4Ḅ
'()*+2x+1<4Ḅ$(3)ᑭᵨaM+bx+c=0Ḅ$ᑭᵨKᦪᑖ᪆
@ᫀ.R⚪T⌕ὃWXYZKᦪ>'()[\ᑭᵨᦪᔠᑖ᪆,⚪ᐵ].22.ூ@ᫀ௃y=-4%+4

16ூ᪆௃(1)^C=0,ᑣy=4,8(0,4),^y=0,ᑣ———3%+4=0,C=1ᡈ%=-4,4(1,0),஺(+4,0),bEcABḄ᪆)y=kx+b,.•.e=4U+b=0f:Y4,•y=-4x+4,ᦑ@ᫀy=-4%+4
(2)y=mx-4m1-p,^x=0,ᑣy=-4m,:.8(0,-4m),^y=0,ᑣC=4,•4(4,0),•GA3h•G(2,2m)fvOC=OA,OB=ODfC(0,4),D(-4m,0),••HCDஹ,/.2),•MG஻h•M(1—m14-m),zvOM="U,/.10=(l-m)2+(l+m)2,m=±2,••m<0,:.m=-2,:.y——2x+8,by=ax2+bx+c,j4(4,0),5(0,-8),஺(8,0)kᐭ(16a+4b+c=0•j64ci+8b+c=0,(c=-8

17a=-Tb=1,ஹc=-81L7to0•y——~x+x—8
(3)ᵫy=—2%+4,n4(2,0),8(0,4),C(0,2),஺(+4,0),by=ax2+bx+c,4a+2b+c=0••16a—4b+c=0c=4(1%a==-2

18ᡠQᙶ᪗(ߟ1,)ᡈ(ߟl,g).(1)
AஹBᙶ᪗NᵫᦪKᦪḄ᪆)ᓽn(2)ᑖ
G(2,2m),(+2m,2),+Nᵫ஺M=n஻?ḄGHnKᦪḄ᪆)(3)ᑖ
Ec/>pᱥcḄ᪆)N
E(—1,|),bF(t,-ᩗ2+t+4),Q(—l,s),ᑖ¢£¤¥¦§জCFz{|}Ḅr~cQ(-19)ঝC஺z{|}Ḅr~c7<2(-1^).⚪ὃWYZKᦪḄ®ឋ°±²³´YZKᦪḄ®ឋ°ᳮ¶z{|}Ḅឋ°ᵨᦪKᦪḄ᪆)ᑖ·¦§,⚪Ḅᐵ].23.ூ@ᫀ௃AC=BD50°ூ᪆௃(1)¸⚪¹ºজ᝞1,•••AAOB=COD=50°,•Z.COA=DOB,••OC=OD,OA=OB,MCOAQADOB(SAS),•AC=BD,.W1,BDᓽAC=BDঝ•••¿COZ¿DOB,:.Z-CAO=DBO,•2LAOB=50°,/.Z.OAB+/-ABO=130°,ᙠ4AMBh4AMB=180°-(NCAO+40AB+Z.ABD)=180°-(ADBO+/.OAB+4ABD)=180°-130°=50°,ᦑ@ᫀজ4C=BDঝ50°(2)·ÇÈÉ᝞2,;=<,44MB=90஺ᳮᵫ,DURtAC஺஺h,4஺஺஺=90°,Z.OAB=Z-OCD=:.CD=2DO9OD_V3**•Ì=taonno30=—fᳮÒ=tan30஺=᫔OA3

19OD__OB_T••Ô-37'44஺8=ZTOD=90°,•Z-AOC=#BOD,•
AOC^LBOD,••Õ=Ö=⌲#CAO=LDBO,DUUUᙠØAMBhZ.AMB=180°-(Z.MAB+Z.ABM)=180°-(஻)AB+Z.ABM+#DBO)=90°
(3)ÙÚÛÜজC>MÝᔠ᝞1,(2)AAOCs^BOD,1Ar-•••^AMB=90°,Ö=ÞDUbBD=x,ᑣAC=8%,RtAC஺஺h/.OCD=30",OD=1,ACD=2,BC=%-2,RtAAOBhWAB=30°,OB=>,•••AB=2OB=2V7,ᙠhᵫßàᳮAC2+BC2=AB2,(V3x)2+(x-2)2=(2᜛*᦮ᳮx2-x-6=0,•(x-3)(%+2)=0,**•=3,%2=+2,•AC=3A/3,ঝC>MÝᔠ᝞2,ᳮã4MB=90஺ä=å,

20bBD=x,ᑣAC=V3x,ᙠRtA/IMBhᵫßàᳮAC2+BC2=AB2,(V3x)2+(%+2)2=(2᜛*᦮ᳮ/+%-6=0,•.(%+3)(%—2)=0,%]——3,%2=2,:.AC=2>/3
ᡠACḄæ3çᡈ26.(1)¸⚪¹ºজèéC04gADOB(SZS),AC=B஺Ç1
ঝᵫ¿DOB,NCAO=#DBO,᪷ëì~Ḅᑁ~îᳮ^AMB=180°-(#DBO+NOAB+"BD)=50°
(2)·ÇÈÉᵫNOCD=NOAB=30஺᪷ë¢}ḄÇï(ðᜳ~ï(n¿AOCs^B஺஺ᑣÖ=ᯅ=Þᵫïóì~Ḅឋ°ã4MBḄôᦪDUUD(3)ÙÚÛÜ[\C>õÝᔠᨵ¢£¤¥(2)nAAOCSRBOD,ᑣN4MB=90°,÷=çnACḄæ.DU⚪,ì~Ḅᔠ⚪ὃWXì~ᐰ(îïóḄឋ°îᑨì~ᑁ~îᳮßàᳮùúûᣚ¸⚪⚪Ḅᐵ],ý
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