初二数学应知应会知识点

11231121212212HL3123xyx(x,-y)y(-x,y)(-x,-y).42560603012312344125126123121(2)3341y=k/x(k0)21212123341231121212212HL3123xyx(x,-y)y(-x,y)(-x,-y).45560603012312344125126123121(2)6341y=k/x(k0)21212123371.2.3.4.(1)(2)(3)5.126.127.12348.12308309.12606010.1231234005679008912318045180612310712381239121..23?.11a+b=b+aa-b=-(b-a)(a-b)2=(b-a)2(a-b)3=-(b-a)3.4(1)a2-b2=a+ba-b(2)a2+2ab+b2=(a+b)2,a2-2ab+b2=(a-b)2.5123456.612345678910.7m+n2x2+px+qx2+px+q?1ABABB.2.312.4123.5.6.7.8.91a0=1(a0),a-n=(a0)234-1-2=1-1-3=-1.1210.11?.12.13ax+b=0(a0),x,abxaxb.,abcxyz.14.0.15.16.17.18.1x2=a,xaax1ax2xaax.212003.3a..4aa.00.5a20,|a|00.00.61;(a0)2.7x3=a,xaax.1ax2aa.13812003.9.10.?.11.1212.13.14.12.A1.(1)ADBACBAD=CAD(2)BAD=CADAD2.(1)ADBD=CD(2)BD=CDAD3.(1)ADABCADB=90(2)ADB=90ADABC414.(1)AB+BCAC(2)AB-BCAC5.(1)ABCAB=AC(2)AB=ACABC6.(1)ABCAB=BC=AC(2)AB=BC=ACABC71180234.1234(1)A+B+C=180(2)C=90A+B=90(3)ACD=A+B(4)ACDA158.(1)C=90ABC(2)ABCC=909.(1)C=90CA=CBABC(2)ABCC=90CA=CB1012.(1)ABCEFGAB=EF(2)ABCEFGA=E11SASASAAASSSSHL.123(1)AB=EFB=FBC=FG16ABCEFG(2)(3)RtABCRtEFGAB=EFAC=EGRtABCRtEFG1212.(1)OCAOBCDOACEOBCD=CE(2)CDOACEOBCD=CEOC13.(1)EFABEFABOA=OB(2)EFABOA=OBEFAB1412.(1)MNABPA=PB(2)PA=PBPAB171512360.123(1)AB=ACB=C(2)AB=ACBAD=CADBD=CDADBC(3)ABCA=B=C=601612360430.1234(1)B=CAB=AC(2)A=B=CABC(3)A=60AB=ACABC(4)C=90B=30AC=AB1712.(1)ABCEGFMNABCEGF(2)ABCEGFMN18OA=OEMNAE181abca2+b2=c22:a2+b2=c2.(1)ABCa2+b2=c2(2)a2+b2=c2ABC19Rt12.(1)ABCDABCD=AB(2)CD=AD=BDABCB.1.2..3CDABBECACD?AB=BE?CA.4.5.6304560.71AC?CB=CD?AB21=B2=A.198.9.10.11.12AAASSA.131234.14123456.15SASASAAASSSSHL.16.17123.181.2.BDBABE=BCDDEBCABE.3ADBCDDEACABEADEDE=ADCEADSABD=SADC20(4)ABCAB=ACABCADABCDE.5ABCDECEABBDACEBCDCD=BCADab,AC,BC,C=90..1.:,.2.:..1.,,.2.:,.3.:SSS[]21SAS[]ASA[]AAS[]HL[,]4.:.5.:..1.,..1.,,..[].2.,,.,,.3.,.,.,.4..5...1.,.2.,.3.:.4.:,.5.:,.,,.,,,.6.:,.,,.,..7.:[],,[][,(,,).22...,,.]8.:,[].[,.]9.:,60.10.:,60..60.11.:,30,.12.,,,..1.(x,y)(-x.-y)x(x,-y)y(-x,y)2...1.,xa,x2=a,xa.a.2.,a,a,a,.3.,a,a.,.4...5..6..7....1..2.,,.3.,.4.,.235.a-a[a],,;00..1..2.0,1;00,;,,00.3.;;..1.,,.2.,,xy,x,y,x,yx.x=ay=b,ba.3.,y=kx[k,k0],.k.[]4.y=kx+b[k,b,k0],..1.:(1)y=3x+1(2)0(3)(4)2.:(1)(2)(3)3.,y=kx[k,k0],y=kx,k0,y=kx,yx;k0,y=kx,yx.4..5..[2x+5=17]:2x-12=0y=2x-12,y=x-12x(6,0)x=66.[5x+63x+10]1:2x-40y=2x-4,x2y=2x-4x2x-40x224x22:y1=5x+6,y2=x+10,x2,y1y2,y1y25x+63x+10x27.:{[xy],(1,1){{x=1,y=1{x=1,y=1.1.,.2..3..4...1.(1).am?an=am+n[m,n],,.(2).(am)n=amn[m,n],,.(3).(ab)n=anbn[n],,.(4).ac5?bc2=(a?b)?(c5?c2)=abc5+2=abc7,,,,.(5).m(a+b+c)=ma+mb+mc,,,(6).(a+b)(m+n)=am+an+bm+bn,,.2.(1).(a+b)(a-b)=a2-b2:,.(2).(ab)2=a22ab+b2:[],,[]2.3.(1)aman=am-n[a0,m,n,mn],,.(2)a0=1[a0]25001.(3),,,.(4),,.4.,,..1.(x+p)(x+q)=x2+(p+q)x+pq2.x3-y3=(x-y)(x2+xy+y2)3.:(1).:,,.(2).a2-b2=(a+b)(a-b),a22ab+b2=(ab)2[]2,[]..1.,,;,..1.:,.2.:..1.,,.2.:,.3.:SSS[]SAS[]ASA[]AAS[]HL[,]4.:.5.:..1.,..261.,,..[].2.,,.,,.3.,.,.,.4..5..