初三数学知识点总结

:.word..1113x2+5x-2=0-2.23x2+4x-2=04-2.33x2-5x-7=03-7.43x(x-1)-2=-4x3x2-x-2=0.21A30y2x0.3A11.4A-23.5A-21.31x=2,y=32x1.2x=3,y=21x1.3x=-1,y=321x1.41y=-8x.2y=4x+1.3xy21.4y=-3(x-2)2-5.5y=4(x-3)2-10x=3.62)1(212xy(1,2).7xy2.5113,10,12,8,710.23,4,2,4,44.3123453.61cos30=23.2sin260+cos260=1.32sin30+tan45=2.4tan45=1.5cos60+sin30=1.:.word..271.2.3.4.5.6.7.8.9.1081,.2.3.4.5.6.7.8.91,.2.3,.4,.5.10160.2.3.4.111042x.Ax=2Bx=-2Cx1=2,x2=-2Dx=42x2-1=0.Ax=1Bx=-1Cx1=1,x2=-1Dx=23x-3x+4=0.A.x1=-3,x2=4B.x1=-3,x2=-4C.x1=3,x2=4D.x1=3,x2=-44x(x-2)=0.Ax1=0,x2=2Bx1=1,x2=2Cx1=0,x2=-2Dx1=1,x2=-25x2-9=0.:.word..3Ax=3Bx=-3Cx1=3,x2=-3Dx1=+3,x2=-312102342xx.A.B.C.D.2,3x2-5x+3=0.A.B.C.D.3,3x2+4x+2=0.A.B.C.D.4,4x2+4x-1=0.A.B.C.D.5,5x2-7x+5=0.A.B.C.D.6,5x2+7x=-5.A.B.C.D.7,x2+4x+2=0.A.B.C.D.8.,5y2+1=25yA.B.C.D.9.4)3(5322xxxx,32xx=y,.A.y2-5y+4=0B.y2-5y-4=0C.y2-4y-5=0D.y2+4y-5=010.4)3(5322xxxx,23xx=y,.A.5y2-4y+1=0B.5y2-4y-1=0C.-5y2-4y-1=0D.-5y2-4y-1=011.(1xx)2-5(1xx)+6=01xx=yy.A.y2+5y+6=0B.y2-5y+6=0C.y2+5y-6=0D.y2-5y-6=01312xyx.A.x2B.x-2C.x-2D.x-2:.word..42y=31x.A.x3B.x3C.x3D.x3y=11x.A.x-1B.x-1C.x1D.x-14y=11x.A.x1B.x1C.x1D.x5y=25x.A.x5B.x5C.x5D.x141,.A.y=-8xB.y=-8x+1C.y=8x2+1D.y=x82,.A.y=8x2B.y=8x+1C.y=-8xD.y=-x83y=8x2y=8x+1y=-8xy=-x8.,.A.1B.2C.3D.4151ABCDO,C=80,A.A.50B.80C.90D.1002O,BAD=50,BCD.A.100B.130C.80D.503O,BOD=100,BCD.A.100B.130C.80D.504ABCDO.A.A+C=180B.A+C=90C.A+B=180D.A+B=9055cm,6cm,.A.3cmB.4cmC.5cmD.6cm6BAD=50,BOD.A.100B.130C.80D.507O,AB100,ACB.A.100B.130C.200D.508.O,BCD=130,BOD.A.100B.130C.80D.509.O,AB8cm,OAB3cm,Ocm.?DBCAO??BOCAD?CBAO?BOCAD?BOCAD?BOCAD?CBAO:.word..5A.3B.4C.5D.1010.O,AB100,ACB.A.100B.130C.200D.50125cm,6cm,.A.3cmB.4cmC.5cmD.6cm161O10,O10,.A.B.C.D.26.5cm,l7cm,.A.B.C.D.3O6.5cm,PO=6cm,PA.B.C.D.46.5cm,l4.5cm,.A.0B.1C.2D.5acm,acm2cm,.A.B.C.D.66.5cm,l6cm,.A.B.C.D.7.6.5cm,l4cm,.A.B.C.D.8.O7cm,PO=14cm,PO.A.B.C.D.171O1O23cm4cmO1O2=10cm.A.B.C.D.2O1O23cm4cm,O1O2=9cm,.A.B.C.D.3O1O23cm5cm,O1O2=1cm,.A.B.C.D.4O1O23cm4cm,O1O2==7cm,.A.B.C.D.5O1O23cm4cm43.A.B.C.D.6O1O22cm6cm,O1O2=6cm,.A.B.C.D.181.A.1B.2C.3D.42.A.1B.2C.3D.4:.word..63.A.1B.2C.3D.44.A.1B.2C.3D.45.O1O23cm4cm,O1O2=9cm,.A.1B.2C.3D.46O1O23cm4cm,O1O2=7cm,.A.1B.2C.3D.4191O10cm.A.5cmB.10cmC.10cmD.5cm22,.A.2B.3C.1D.23,2,.A.2B.1C.2D.3432,2,=.A.30B.60C.90D.1205,R,.A.21RB.RC.2RD.R36C,S=.A.2CB.2CC.22CD.42C7.A.1:2B.1:3C.3:2D.1:28.C,R=.A.2CB.CC.2CD.C9.,2,.A.2B.4C.22D.2310,3,.A.3B.3C.32D.33201x32cbxax21xcbxaxy2x=2.:.word..7A.(2-3)B.(21)C.(23)D.(32)2y=2(x-3)2+2,.A.(-3,2)B.(-3,-2)C.(3,2)D.(3,-2)3y=x+1.A.B.C.D.4y=2x+1.A.B.C.D.5y=x2.A.B.C.D.6y=-x10.AB.C.D.7y=2(x-3)2+2,.A.(-3,2)B.(-3,-2)C.(3,2)D.(3,-2)8y=-x+1.AB.C.D.9y=-2x+1.AB.C.D.10.y=ax2+bx+ca0abcx=1A(-1,y1)B(21,y2)C(2,y3)y1y2y3.A.y3y1y2B.y2y3y1C.y3y2y1D.y1y3y2211)4)(4(yxxyyxyxxyyx.A.22xyB.22yxC.224yxD.224yx2.1-121)11222aaaaaa.A.aa2B.aa2C.-aa2D.-aa23.)21(22xxx.A.xB.x1C.-x1D.-xx24.)111()111(2xx.A.1B.x+1C.xx1D.11x:.word..85)11()111(xxxx.A.1xxB.-1xxC.1xxD.-1xx6.)11()(yxxyyyxx.A.yxxyB.-yxxyC.yxxyD.-yxxy7.22222222222)(yxyxxyyxyxyxyxyx.A.x-yB.x+yC.-(x+y)D.y-x8.)1(1xxxx.A.1B.11xC.-1D.11x9.xxxxxx24)22(.A.21xB.21xC.-21xD.-21x221.xy02xyx.A.yB.yC.-yD.-y2.21aaa.A.1aB.-1aC.1aD.1a3.ababa.A.abB.-abC.abD.-ab4.abababaa2)(.A.aB.-aC.aD.a:.word..95.23)1(xx.A.xxx1B.xxx1C.xxx1D.1xxx6abababaa2)(.A.aB.-aC.aD.a7xy0,yx2.A.yxB.-yxC.yxD.yx8abababaa2)(.A.aB.-aC.aD.a9baa2ab.A.abaB.abaC.abaD.aba1021aaa.A.1aB.-1aC.1aD.1a11ab0321baa.A.bbB.-bbC.bbD.-bb231m=xxmxx2312422.A.1B.2C.-1D.22xxxx23121422.A.x=-2x=0B.x=-2C.x=0D.305)1(2122xxxxxx1=yy.A.y2+2y-5=0B.y2+2y-7=0C.y2+2y-3=0D.y2+2y-9=04(a-1)x2+2ax+a2+5=0x=-3a.A.-4B.1C.-41D.4-1:.word..105x0111xax,a.A.a=1B.a=-1C.a=1D.a=261-2-32-3.A.x2+23x-1=0B.x2+23x+1=0C.x2-23x-1=0D.x2-23x+1=07x(k-3)x2-2kx+k+1=0k.A.k-23B.k-23k3C.k-23D.k23k3241P(2,2)PQxPQ=2Q.A.(4,2)B.(0,2)(4,2)C.(0,2)D.(2,0)(2,4)2Px3,y4,P,P.A.(3,-4)B.(-3,4)C.4,-3)D.(-4,3)3P(1,-2)xl1,Q(-4,3)yl2,l1l2AA.A.(1,3)B.(-4,-2)C.(3,1)D.(-2,-4)251A(-1,y1)B(-41,y2)C(21,y3)y=xk(k0).A.y3y1y2B.y2+y30C.y1+y30D.y1?y3?y202y=xm63A(x1,y1)B(x2,y2),x20x1,y1y2,m.A.m2B.m2C.m0D.m03:,Oy=x2AB,ACx,ADy,ABCS,.A.S=2B.2S4C.S=4D.S44(x1,y1)(x2,y2)y=-x2,:;yx;0x1x2,y1y2;(-x1,-y1)(-x2,-y2),.A.1B.2C.3D.45xkyy=-x+2ABAOB90ok.A.k1B.k1C.0k1D.k06(mm1)xnny122y=-x+b|b|2.A.0B.1C.2D.4:.word..117bkxyxkyAx1y1,Bx2y2,x1x2.A.kbB.kbC.kbD.kb261.A.B.C.D.2.,.A.2,1B.1,2C.1,3D.3,13.A.B.C.D.4..A.B.C.D.5,,...A.2B.3C.4D.66,..A.B.C.D.7.A.B.C.D.8.A.B.C.D.9..A.B.C.D.271,,(:):100,98,108,96,102,101.2000,.A.2105B.61052,,(:):25,21,18,19,24,19.200,.:.word..1228160.A.45B.51C.54D.57225010010.540.020.10.120.46.271522.526.522.526.5..A.B.C.D.3nnn+1,..A.10;B.13;C.,8;D.,1112.4,50(),12421,,,.1569.579.50.4;90(90),5.ABCD5(),13642660(60).A.43B.44C.45D.48660.A45B51C54D577(),,,50;49.559.50.08;79.589.5;(80)56%.A.B.C.D.8,,(1),,(10.514.518.522.526.530.559.569.579.589.599.549.50.150.050.250.100.3049.559.569.579.589.599.5100681012141624681081216249.559.569.579.589.599.51.791.591.992.192.392.5949.559.569.579.589.599.5:.word..13)40.050.150.300.359,2(2).(1)60;0.15;80%.A.B.C.D.29112.89%9%.%918.12..A.B.C.D.2200216.3,20011