搜索
(2)(7,42)1.xyz,xy(y+z)(z+x)+yz(z+x)(x+y)+zx(x+y)(y+z)=1,xyz().(A)(B)(C)(D)2.1,ABC,BC=1,A=30,DBC,GABC.BC,A,GD().1(A)0GD136(B)16GD136(C)0GD2+36(D)16GD2+563.ab,a+ba+5b-2.(a,b)().(A)0(B)1(C)2(D)34.y=ax2+bx+c(a0)y=k(x-1)-k24.k,.,().(A)y=x2(B)y=x2-2x(C)y=x2-2x+1(D)y=2x2-4x+25.x,{x}=x-[x]([x]x),2006x+{x}=12007().(A)0(B)1(C)2(D)226.2,ABCDO,PCD,PABDM,PBACN,PAC=.MNPA,2cos2-tan().(A)1(B)22(C)12(D)24(7,28)1.xy,(x+x2+2008)(y+y2+2008)=2008.x2-3xy-4y2-6x-6y+2008.2.abca+b+c=0,abc=2.u=|a|3+|b|3+|c|3.3.,A(-3,0)B(3,0),Py=33(x+4)+1520071©1994-2007ChinaAcademicJournalElectronicPublishingHouse.Allrightsreserved.=1720.abc=.(20)mn,mn,2006m2+m=2007n2+n.m-n?.(25)3,ABCD,ABCD,AD=12,ECD,CEED=354.ABCEO1R1,ACDO2R2,BCO2.(1)CD;(2)R1R2.(25)a,f(x)=(x+a)(|x-a+1|+|x-3|)-2x+4a.1.D.,(x+y)(y+z)(z+x)0.xy(x+y)+yz(y+z)+zx(z+x)=(x+y)(y+z)(z+x).xyz=0.,xyz.xyz,x+yy+zz+x,.xyz.2.B.4A=30,ABC,,A4A1BA2C(,A1BBC,A2CBC).G1RtA1BC,13BDGDG1D.A1B=3,G1D=13A1D=13A1B2+BD2=136.13BD=16,,16GD136.3.A.a+b,(a+b)2=(a+5)2+(b-2)2,2(ab-5a+2b)=29.,,.a+5,(a+5)2=(a+b)2+(b-2)2,2(5a-ab-b2+2b)=-21..b-2,(b-2)2=(a+b)2+(a+5)2,2(a2+ab+5a+2b)=-21..(a,b).4.C.y=ax2+bx+c,y=k(x-1)-k24ax2+(b-k)x+c+k+k24=0.,,=(b-k)2-4ac+k+k24=0,(1-a)k2-2(2a+b)k+b2-4ac=0.k,,6©1994-2007ChinaAcademicJournalElectronicPublishingHouse.Allrightsreserved.=0,2a+b=0,b2-4ac=0.a=1,b=-2,c=1.y=x2-2x+1.5.C.x=[x]+{x},,2006[x]+2007{x}=12007.02007{x}2007,,[x]=-1[x]=0.[x]=-1,{x}=20062007+120072=20072-2007+120072=1-2006200721.,x=-1+1-200620072=-200620072.[x]=0,{x}=120072,x=120072.,x1=-200620072,x2=120072.6.A.O1,AC=2.2,PC.APC=90.,PA=ACcos=2cos.RtAOM,AM=OAcos=1cos;RtAMN,MN=AMtan=tancos;RtPMN,MPN=APB=ADB=45,,PM=MN=tancos.AM+PM=PA,1cos+tancos=2cos.2cos2-tan=1.1.2008.x+x2+2008=2008y+y2+2008.x+x2+2008=y2+2008-y.,y+y2+2008=x2+2008-x.+x+y=0.x2-3xy-4y2-6x-6y+2008=(x+y)(x-4y)-6(x+y)+2008=2008.2.10.,abc.a0b0c0.b+c=-a,bc=2a,,bcx2+ax+2a=0.,=a2-8a0.a38.u=a3-b3-c3=a3-(b+c)[(b+c)2-3bc]=a3+aa2-6a=2a3-628-6=10.a3=8,a=2,.,b=c=-1.,u10.3.3-1.55,xM.,APB,ABPP.MPA=MBP,,MPAMBP.PAPB=MPMB.MP2=MAMB.PAPB=MP2MB2=MAMB.M(-4-3,0)A(-3,0)B(3,0),,MA=4,MB=4+23.PAPB=44+23=23+1=3-1.720071©1994-2007ChinaAcademicJournalElectronicPublishingHouse.Allrightsreserved.=b2,c2-b2=a2,,1720=bc+a+ac+b=b(c-a)c2-a2+a(c-b)c2-b2=c-ab+c-ba=c(a+b)-(a2+b2)ab=c(a+b-c)ab.ab=(a+b)2-(a2+b2)2=(a+b)2-c22=12(a+b+c)(a+b-c),,1720=2ca+b+c,17(a+b)=23c.289(a2+2ab+b2)=529c2=529(a2+b2).(15a-8b)(8a-15b)=0.,ab=815ab=158.82+152=172,abc,abc=81517.m-n.:m=n+k(k).2006m2+m=2007n2+n,n2-22006kn-(2006k2+k)=0.n,,=4(2006k)2+4(2006k2+k).4=k[(20062+2006)k+1].(k,(20062+2006)k+1)=1,,k(20062+2006)k+1.m-n.(1)BCO2,,ACB=CDA.ABCD,BAC=ACD.,ABCCAD.,ABC=CAD.ADO1.AD2=DEDC.122=49DC2.CD=18.(2)(1),ABCCAD,CD=18.,R1R2=ACCD,R1R2=AC18.6=CD-ADACCD+AD=30,,13R1R253.ACCD(,ABCD),,R1R21.R1R213R1R253,R1R21.,max{a1,a2,,an}min{a1,a2,,an}a1,a2,,an.xmin{a-1,3},f(x)=(x+a)(-2x+a+2)-2x+4a=-2x2-ax+a2+6a.xmax{a-1,3},f(x)=(x+a)(2x-a-2)-2x+4a=2x2+(a-4)x-a2+2a.min{a-1,3}xmax{a-1,3},f(x).,f(x),.M,ABM,f(x).xM=(a-1)+32=a+22,xA=-a4,xB=-a-44,,xA+xB2=xM,-a+(a-4)8=a+22.a=-23.,a=-23.(,710054,713100)8©1994-2007ChinaAcademicJournalElectronicPublishingHouse.Allrightsreserved.